A safety precaution designed to prolong the life of a lead acid accumulator is

C. Keeping the specific gravity of the electrolyte within specified range

A. By topping up the cells with concentrated acid

B. The use of naked flame when charging the battery

C. Keeping the specific gravity of the electrolyte within specified range

D. By connecting wires to the terminals directly when testing the level of charging

During the transformation of matter from the solid to the liquid state, the heat supplied does not produce temperature increase because

A. all the heat is used to break the bonds holding the molecules of the solid together

B. the heat capacity has become very large as the substance melts

C. the heat energy is quickly conducted away

D. the heat gained is equal to the heat lost by the substance

The Earth's magnetic equator passes through Jos in Nigeria. At Jos, the

D. horizontal component at the Earth's field is zero

Gases conduct electricity under

A. high pressure & high voltage

C. normal pressure & low voltage

Which of these is observed when air is pumped out of a discharge tube without lowering its pressure

A. the conductivity of the air increases

B. the conductivity of the air decreases

If the attraction of the sun is suddenly ceased, the earth would continue to move in a straight line making a tangent with the original orbit. This statement is derived from Newton's

D. Law of universal gravitation

A man on a bench will exert the greatest pressure on the bench when he

D. stands on the toes of one foot

According to kinetic molecular model, in gases

A. The molecule are very fast apart & occupy all the space made available

B. The particles occur in clusters with molecules slightly farther apart

C. The particles vibrate about fixed positions and are held together by the strong intermolecular bond between them

D. The particles are closely packed together, they occupy minimum space & are usually arranged in a regular pattern

A body was slightly displaced from its equilibrium position. Which one of the following is a condition for its stable equilibrium

B. an increase in the potential energy of the body

A. an increase in the kinetic energy of the body

B. an increase in the potential energy of the body

C. a decrease in the kinetic energy of the body

D. an increase in the height of the body

Workdone on an object to bring it to a certain point in space is called

A. Gravitational potential energy

The angular dispersion of a prism depends on

B. The angle of incidence as well as the index of refraction

A. The index of refraction only

B. The angle of incidence as well as the index of refraction

D. The thickness of the prism only

An alternating current can induce voltage because it has

C. weaker magnetic field than direct current

The pin-hole camera produces a less sharply defined image when the

C. screen is further from the pin-hole

D. object is further from the pin-hole

Which of the following equations is the correct definition of the reactance of an indicator L?

A. Reactance = (Amplitude of voltage) $\div$ (Amplitude of current)

B. Reactance = (Amplitude of voltage) x (Amplitude of current)

C. Reactance = (Amplitude of current)$^2$ $\div$ (Amplitude of voltage)

D. Reactance = (Amplitude of current)$^2$ $\div$ (Amplitude of voltage)$\frac{1}{2}$

JAMB 2019 · Part 1 of 2

2019 JAMB Physics Past Questions

The 2019 JAMB Physics past questions with answers: 101 objective questions from the 2019 paper in the DeeepSolve question bank, each with its answer behind "Show answer". This is part 1 of 2: questions 1 to 51. Try each question before you check, then practise the paper as a timed JAMB-style CBT.

Practise this paper as a timed JAMB-style CBT All JAMB Physics years

Questions 1–51

1.
A car moving at 20m/s with its horn blowing (f = 1200Hz) is chasing another car going at 15m/s. What is the apparent frequency of the horn as heard by the driver being chased?
1. A.1.22KHz
2. B.2.40KHz
3. C.8.12KHz
4. D.1.22Hz
Show answer
Answer: A. 1.22KHz
AI explanation
1. Analyze the Question
We are dealing with the Doppler Effect, which describes the change in frequency of a wave in relation to an observer who is moving relative to the wave source.
Source (Car 1): Moving at $v_s = 20 \, \text{m/s}$ , Frequency $f_s = 1200 \, \text{Hz}$ .
Observer (Car 2): Moving at $v_o = 15 \, \text{m/s}$ .
Speed of Sound ( $v$ ): Standard value is $340 \, \text{m/s}$ (unless otherwise specified in the exam).
2. Explain the Concept
The formula for the Doppler Effect is:
$f_o = f_s \left( \frac{v \pm v_o}{v \mp v_s} \right)$
Numerator ( $v \pm v_o$ ): Since the observer is moving away from the source, the frequency decreases, so we use the minus sign ( $v - v_o$ ).
Denominator ( $v \mp v_s$ ): Since the source is moving towards the observer, the frequency increases, so we use the minus sign ( $v - v_s$ ).
So, the formula becomes:
$f_o = f_s \left( \frac{v - v_o}{v - v_s} \right)$
3. Show the Solution
$f_s = 1200 \, \text{Hz}$
$v = 340 \, \text{m/s}$
$v_o = 15 \, \text{m/s}$
$v_s = 20 \, \text{m/s}$
Substitute the values into the formula:
$f_o = 1200 \left( \frac{340 - 15}{340 - 20} \right)$
$f_o = 1200 \left( \frac{325}{320} \right)$
$f_o = 1200 \times 1.015625$
$f_o = 1218.75 \, \text{Hz}$
Convert to Kilohertz (KHz):
$1218.75 \div 1000 \approx 1.21875 \, \text{KHz}$
Rounding to two decimal places, we get 1.22 KHz.
4. Identify the Answer
Comparing our result to the options provided, the value matches option A.
5. Tip
Memory Trick: Think of the "Doppler Sign Convention":
Towards = Increase: If the movement makes the sound pitch higher (closer), the math must result in a larger number.
Away = Decrease: If the movement makes the sound pitch lower (further), the math must result in a smaller number.
Always check if the question asks for Hz or KHz to avoid picking the wrong unit (like option D).
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2.
A microscope is focused on a mark on a table, when the mark is covered by a plate of glass 2m thick, the microscope has to be raised 0.67cm for the mark to be once more in focus. Calculate the refractive index.
1. A.1.50
2. B.1.68
3. C.2.58
4. D.1.82
Show answer
Answer: A. 1.50
AI explanation
Analysis
This is a classic optics problem involving apparent depth. When a transparent medium (like a glass plate) is placed over an object, the object appears to be raised. The microscope must be moved upward to compensate for this shift so that it can focus on the "apparent" position of the mark.
Concept
The formula for the apparent shift ( $s$ ) caused by a glass plate of thickness ( $t$ ) and refractive index ( $n$ ) is:
$s = t \left(1 - \frac{1}{n}\right)$
Where:
$s$ = shift (the distance the microscope is raised) = $0.67\text{ cm}$
$t$ = real thickness of the glass = $2\text{ cm}$
$n$ = refractive index of the glass
Solution
Convert units: Ensure all units are consistent. Here, both $s$ and $t$ are in centimeters, so we can proceed directly.
Set up the equation: $ $0.67 = 2 \left(1 - \frac{1}{n}\right)$ $
Solve for $n$ : Divide both sides by 2: $ $\frac{0.67}{2} = 1 - \frac{1}{n}$ $ $ $0.335 = 1 - \frac{1}{n}$ $
Rearrange to isolate $1/n$ : $ $\frac{1}{n} = 1 - 0.335$ $ $ $\frac{1}{n} = 0.665$ $
Calculate $n$ : $ $n = \frac{1}{0.665} \approx 1.5037$ $
Rounding to two decimal places, we get 1.50.
Conclusion
Comparing our result to the options provided, the correct value is 1.50.
Exam Tip
When dealing with "apparent depth" or "shift" problems, always remember that the shift is the difference between the real depth and the apparent depth. If you ever forget the formula, just remember: Shift = Real Depth - Apparent Depth, where Apparent Depth = $\frac{\text{Real Depth}}{n}$ .
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3.
A safety precaution designed to prolong the life of a lead acid accumulator is
1. A.By topping up the cells with concentrated acid
2. B.The use of naked flame when charging the battery
3. C.Keeping the specific gravity of the electrolyte within specified range
4. D.By connecting wires to the terminals directly when testing the level of charging
Show answer
Answer: C. Keeping the specific gravity of the electrolyte within specified range
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4.
One newton × One meter equals?
1. A.One water
2. B.One Joule
3. C.One ampere
4. D.One kilogram
Show answer
Answer: B. One Joule
AI explanation
1. Analyze the question
The question asks for the physical unit equivalent to the product of one newton (unit of force) and one meter (unit of distance/displacement).
2. Explain the concept
In Physics, Work Done is defined as the product of the force applied to an object and the displacement of the object in the direction of the force.
The formula is:
$W = F \times d$
Where:
W = Work Done
F = Force (measured in Newtons, N)
d = Displacement (measured in meters, m)
Since the unit of force is the Newton (N) and the unit of displacement is the meter (m), the unit for Work Done is Newton-meter (N·m). By international convention (SI units), this unit is named the Joule (J) in honor of the physicist James Prescott Joule.
3. Show the solution
Force = 1 Newton (N)
Distance = 1 meter (m)
Work = Force × Distance
Work = 1 N × 1 m = 1 N·m
Since 1 N·m is defined as 1 Joule:
1 N·m = 1 Joule
4. Identify the answer
Comparing our result to the given options: A. One water (Incorrect) B. One Joule (Correct) C. One ampere (Incorrect - this is the unit of electric current) D. One kilogram (Incorrect - this is the unit of mass)
The correct option is B.
5. Exam Tip
Remember the acronym "WFD" (Work = Force × Displacement). Whenever you see units multiplied together in physics, check if they represent a derived SI unit. A Newton-meter is the same as a Joule, and it is also the same unit used for Torque (though torque is a vector quantity and work is a scalar, they share the same dimensional unit).
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5.
Heat may be transferred by conduction, convection and radiation. By which of these methods does heat travel through vacuum?
1. A.Conduction only
2. B.Convection only
3. C.Radiation only
4. D.All these methods
Show answer
Answer: C. Radiation only
AI explanation
Analysis
The question asks us to identify which method of heat transfer can occur in a vacuum. A vacuum is a space entirely devoid of matter (no particles).
Concept Explanation
To understand this, we must look at the requirements for each method of heat transfer:
Conduction: This is the transfer of heat through a material medium (usually solids) by the vibration of atoms or the movement of free electrons. It requires particles to pass the energy along. Therefore, it cannot occur in a vacuum.
Convection: This is the transfer of heat in fluids (liquids and gases) through the actual movement of the heated particles themselves. Since it requires a medium (fluid) to carry the heat, it cannot occur in a vacuum.
Radiation: This is the transfer of heat in the form of electromagnetic waves (specifically infrared radiation). Electromagnetic waves do not require a material medium to propagate; they can travel through empty space at the speed of light. This is how heat from the Sun reaches the Earth through the vacuum of space.
Step-by-Step Solution
Step 1: Evaluate Conduction. It requires physical contact between particles. No particles = no conduction.
Step 2: Evaluate Convection. It requires a fluid medium to circulate. No fluid = no convection.
Step 3: Evaluate Radiation. It uses electromagnetic waves, which are self-propagating and do not need a medium.
Step 4: Conclude that only radiation is capable of transferring heat through a vacuum.
Conclusion
Based on the principles of thermodynamics, radiation is the only method of heat transfer that does not require a medium.
Exam Tip: Always remember the "Sun" analogy. If you are ever confused about radiation, just think: "How does the Sun warm the Earth?" The space between the Sun and Earth is a vacuum, so it must be radiation!
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6.
The statement 'Heat lost by the hot body equals that gained by the cold one' is assumed when determining specific that heat capacity by the method of mixtures. Which of the following validates the assumption? I. Lagging the Calorimeter II. Ensuring that only S.I units are used III. Weighing the calorimeter, the lid and the stirrer.
1. A.I only
2. B.I & II only
3. C.I & III only
4. D.II & III only
Show answer
Answer: A. I only
AI explanation
Analysis
The question asks us to identify which of the listed actions validates the principle of calorimetry (the method of mixtures), which states that the heat lost by a hot body equals the heat gained by a cold body. This principle is based on the Law of Conservation of Energy.
Concept Explanation
In the method of mixtures, we assume that the system is isolated—meaning no heat is exchanged with the surroundings. If heat escapes to the environment (or is absorbed from it), the calculation will be inaccurate because the heat lost will not equal the heat gained.
Lagging the calorimeter: This involves wrapping the calorimeter in insulating material (like cotton wool or felt). This prevents heat loss to the surroundings via conduction or convection. This is essential to validate the assumption that all heat lost by the hot body is gained by the cold body and the calorimeter.
Ensuring only S.I. units are used: While using standard units is important for calculation accuracy, it is a matter of mathematical convention and does not physically prevent heat loss or validate the thermodynamic assumption of an isolated system.
Weighing the calorimeter, lid, and stirrer: This is necessary to determine the mass of the components so that their individual heat capacities can be calculated. While this is a crucial step in the procedure of the experiment, it does not validate the assumption that heat lost equals heat gained; rather, it allows us to account for the heat absorbed by the apparatus itself.
Step-by-Step Solution
Evaluate I: Lagging the calorimeter directly addresses the "isolated system" requirement. By minimizing heat exchange with the environment, we ensure the energy balance remains valid. Therefore, I is correct.
Evaluate II: Using S.I. units is a standard practice for consistency, but it has no physical effect on the heat transfer process. Therefore, II is incorrect.
Evaluate III: Weighing the components is a measurement step to ensure we have the correct data for our calculation. It does not prevent heat loss or validate the principle of energy conservation. Therefore, III is incorrect.
Since only statement I validates the assumption that heat lost equals heat gained by preventing external interference, the correct choice is I only.
Exam Tip
When dealing with calorimetry questions, always remember the "Law of Conservation of Energy." Any step that minimizes heat loss (like using a lid or lagging) is about validating the assumption, while any step involving measurement (like weighing) is about data collection.
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7.
In semi-conductor, the carriers of current at room temperature are
1. A.electrons only
2. B.electrons and holes
3. C.holes only
4. D.electron and ions
Show answer
Answer: B. electrons and holes
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8.
The earth's gravitational field intensity at its surface is about (G = 6.7 × 10 $^{-11}$ Nm $^2$ /kg $^2$ , mass of the earth is 6 × 10 $^{24}$ kg, radius of the earth is 6.4 × 10 $^6$ m, g on the earth = 9.8m/s $^2$ )
1. A.6.7N/kg
2. B.7.9N/kg
3. C.8.0N/kg
4. D.9.8N/kg
Show answer
Answer: D. 9.8N/kg
AI explanation
Analysis
The question asks for the gravitational field intensity ( $g$ ) at the surface of the Earth. Gravitational field intensity is defined as the force per unit mass exerted by a gravitational field.
Concept
The formula for gravitational field intensity ( $g$ ) at the surface of a planet is derived from Newton's Law of Universal Gravitation:
$g = \frac{GM}{R^2}$
Where:
$G$ = Universal gravitational constant ( $6.7 \times 10^{-11} \, \text{Nm}^2/\text{kg}^2$ )
$M$ = Mass of the Earth ( $6 \times 10^{24} \, \text{kg}$ )
$R$ = Radius of the Earth ( $6.4 \times 10^6 \, \text{m}$ )
Solution
Let's plug the given values into the formula:
Calculate the numerator ( $G \times M$ ): $G \times M = (6.7 \times 10^{-11}) \times (6 \times 10^{24})$ $G \times M = 40.2 \times 10^{13}$ $G \times M = 4.02 \times 10^{14}$
Calculate the denominator ( $R^2$ ): $R^2 = (6.4 \times 10^6)^2$ $R^2 = 40.96 \times 10^{12}$ $R^2 = 4.096 \times 10^{13}$
Divide the results: $g = \frac{4.02 \times 10^{14}}{4.096 \times 10^{13}}$ $g = \frac{40.2}{4.096}$ $g \approx 9.814 \, \text{N/kg}$
Rounding to one decimal place, we get 9.8 N/kg.
Conclusion
The calculation confirms that the gravitational field intensity at the Earth's surface is approximately 9.8 N/kg, which is equivalent to the acceleration due to gravity ( $9.8 \, \text{m/s}^2$ ).
Exam Tip: Always remember that the units N/kg (Newtons per kilogram) and m/s² (meters per second squared) are equivalent for gravitational field intensity and acceleration due to gravity. If you see either unit in a question about gravity, they are referring to the same physical quantity!
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9.
A metal rod has a length of 100cm at 200°C. At what temperature will its length be 99.4cm. If the linear expansivity of the material of the rod is 2 × 10 $^{-5}$ C $^{-1}$
1. A. $300^0C$
2. B. $200^0C$
3. C. $100^0C$
4. D. $-100^0C$
Show answer
Answer: D. $-100^0C$
AI explanation
Analysis
To solve this problem, we need to use the formula for linear expansion, which describes how the length of a solid changes when its temperature changes.
Concept
The formula for linear expansion is:
$L_2 = L_1(1 + \alpha\Delta\theta)$
Where:
$L_1$ = Initial length (100 cm)
$L_2$ = Final length (99.4 cm)
$\alpha$ = Linear expansivity ( $2 \times 10^{-5} \, ^\circ\text{C}^{-1}$ )
$\Delta\theta$ = Change in temperature ( $\theta_2 - \theta_1$ )
$\theta_1$ = Initial temperature ( $200^\circ\text{C}$ )
$\theta_2$ = Final temperature (what we need to find)
Step-by-Step Solution
1. Identify the change in length ( $\Delta L$ ):
$\Delta L = L_2 - L_1$
$\Delta L = 99.4 - 100 = -0.6 \text{ cm}$
2. Use the linear expansivity formula:
$\Delta L = L_1 \alpha \Delta\theta$
$-0.6 = 100 \times (2 \times 10^{-5}) \times \Delta\theta$
3. Solve for $\Delta\theta$ :
$-0.6 = (100 \times 0.00002) \times \Delta\theta$
$-0.6 = 0.002 \times \Delta\theta$
$\Delta\theta = \frac{-0.6}{0.002}$
$\Delta\theta = -300^\circ\text{C}$
4. Find the final temperature ( $\theta_2$ ): Since $\Delta\theta = \theta_2 - \theta_1$ :
$-300 = \theta_2 - 200$
$\theta_2 = -300 + 200$
$\theta_2 = -100^\circ\text{C}$
Conclusion
The temperature at which the rod will have a length of 99.4 cm is $-100^\circ\text{C}$ .
Exam Tip
Always pay attention to the sign of your change in length ( $\Delta L$ ). If the length decreases, $\Delta L$ must be negative, which will lead to a negative temperature change. Don't let the negative sign confuse you—it simply means the temperature dropped!
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10.
During the transformation of matter from the solid to the liquid state, the heat supplied does not produce temperature increase because
1. A.all the heat is used to break the bonds holding the molecules of the solid together
2. B.the heat capacity has become very large as the substance melts
3. C.the heat energy is quickly conducted away
4. D.the heat gained is equal to the heat lost by the substance
Show answer
Answer: A. all the heat is used to break the bonds holding the molecules of the solid together
AI explanation
Analysis of the Question
The question asks why the temperature of a substance remains constant during the phase change from a solid to a liquid, even though heat is being continuously supplied to it. This is a fundamental concept in thermodynamics known as Latent Heat.
Explanation of the Concept
In physics, when you supply heat to a substance, it usually results in an increase in the kinetic energy of the molecules, which we measure as a rise in temperature. However, during a phase change (like melting or boiling), the substance undergoes a transition where the arrangement of its molecules changes.
Solid state: Molecules are held in a fixed, rigid structure by strong intermolecular forces (bonds).
Melting process: To turn a solid into a liquid, the substance must overcome these strong intermolecular forces.
Latent Heat of Fusion: The energy supplied during this period is called the latent heat of fusion. Instead of increasing the kinetic energy (temperature) of the molecules, this energy is entirely consumed to break the bonds holding the solid structure together, allowing the molecules to move more freely as a liquid.
Step-by-Step Solution
Identify the process: The substance is changing state from solid to liquid (melting).
Apply the principle of energy conservation: Heat supplied ( $Q$ ) = Energy used to increase kinetic energy + Energy used to change state.
Analyze the temperature: Since the temperature does not change, the kinetic energy of the molecules remains constant.
Conclusion: Therefore, all the heat supplied must be used to perform the work of breaking the intermolecular bonds (potential energy change) to transition the substance into a liquid state.
Identifying the Answer
Comparing this to the given options:
Option A correctly describes that the heat is used to break the bonds.
Option B is incorrect because heat capacity is not the factor causing the temperature plateau.
Option C is incorrect because the heat is being absorbed by the substance, not conducted away.
Option D is incorrect because this describes thermal equilibrium, not a phase change.
Exam Tip
Whenever you see a question about "constant temperature" during a phase change (melting or boiling), remember the keyword "Latent". Latent means "hidden"—the heat is "hidden" because it is doing the work of changing the state rather than raising the temperature.
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11.
A vibrator causes water ripples to travel across the surface of a tank. The wave travels 50cm in 2s and the distance between successive crests is 5cm. Calculate the frequency of the vibrator
1. A.5Hz
2. B.6Hz
3. C.5.2Hz
4. D.25Hz
Show answer
Answer: A. 5Hz
AI explanation
1. Analyze the Question
We are given:
Distance ( $d$ ): 50 cm
Time ( $t$ ): 2 s
Wavelength ( $\lambda$ ): 5 cm (the distance between successive crests)
Goal: Calculate the frequency ( $f$ ) of the vibrator.
2. Explain the Concept
To solve this, we use two fundamental wave equations:
Wave Speed ( $v$ ): Speed is the total distance covered divided by the time taken. $ $v = \frac{d}{t}$ $
Wave Equation: The relationship between speed, frequency, and wavelength is: $ $v = f \times \lambda$ $Rearranging this to find frequency, we get:$ $f = \frac{v}{\lambda}$ $
3. Show the Solution
Step 1: Calculate the speed of the wave ( $v$ ).
$v = \frac{50\text{ cm}}{2\text{ s}} = 25\text{ cm/s}$
Step 2: Calculate the frequency ( $f$ ). Using the wave equation $v = f \times \lambda$ :
$25\text{ cm/s} = f \times 5\text{ cm}$
$f = \frac{25}{5}$
$f = 5\text{ Hz}$
4. Identify the Answer
The frequency of the vibrator is 5 Hz. Comparing this to the given options, the correct choice is A.
5. Exam Tip
In wave problems, always check your units. Since the distance and wavelength were both in centimeters (cm), you didn't need to convert to meters, as the units canceled out. However, if the speed was asked for in m/s, you would have needed to convert the distance to meters first. Always keep an eye on those units!
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12.
The Earth's magnetic equator passes through Jos in Nigeria. At Jos, the
1. A.angle of variation is zero
2. B.magnetic declination is 90
3. C.angle of dip is zero
4. D.horizontal component at the Earth's field is zero
Show answer
Answer: C. angle of dip is zero
AI explanation
Analysis of the Question
This question tests your understanding of Terrestrial Magnetism, specifically the concept of the Angle of Dip (or Inclination). You are asked to identify the physical characteristic of the Earth's magnetic field at the magnetic equator.
Concept Explanation
The Angle of Dip is the angle that the Earth's magnetic field makes with the horizontal at any point on the Earth's surface.
At the Magnetic Poles: The magnetic field lines are perpendicular to the Earth's surface. Therefore, the angle of dip is 90°.
At the Magnetic Equator: The magnetic field lines are parallel to the Earth's surface. Because the field is perfectly horizontal, it makes an angle of 0° with the horizontal.
In Nigeria, Jos is geographically significant in physics because it is located very close to the magnetic equator. Consequently, a magnetic needle suspended freely at Jos will remain perfectly horizontal.
Step-by-Step Solution
Step 1: Recall the definition of the magnetic equator. It is the line where the Earth's magnetic field is horizontal.
Step 2: Relate this to the angle of dip. Since the field is horizontal, the angle between the field and the horizontal plane is 0°.
Step 3: Evaluate the options: • A: Angle of variation (declination) is not necessarily zero at the equator; it depends on the specific location. • B: Magnetic declination is the angle between true north and magnetic north; it is not 90° at the equator. • C: The angle of dip is the angle of inclination. At the magnetic equator, this is 0°. This matches our definition. • D: The horizontal component of the Earth's field is at its maximum at the equator, not zero. (The vertical component is zero at the equator).
Conclusion
Since the magnetic field is horizontal at the magnetic equator, the angle of dip is 0°. This confirms that option C is the correct statement.
Exam Tip
Remember the "90-0-90" rule for the Earth's magnetic field:
At the Poles, the angle of dip is 90°.
At the Equator, the angle of dip is 0°.
If you ever forget, visualize a compass needle: at the equator, it stays flat (0°), but if you were at the North Pole, it would try to point straight down into the ground (90°).
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13.
Gases conduct electricity under
1. A.high pressure & high voltage
2. B.low pressure & low voltage
3. C.normal pressure & low voltage
4. D.low pressure & high voltage
Show answer
Answer: D. low pressure & high voltage
AI explanation
Analysis
The question asks for the specific physical conditions required for a gas, which is normally an insulator, to become a conductor of electricity.
Concept Explanation
Under normal conditions (standard atmospheric pressure and temperature), gases are excellent insulators because their molecules are neutral and far apart, meaning there are no free charge carriers to conduct electricity.
To make a gas conduct electricity, you must create ions (charged particles). This is achieved through a process called ionisation.
Low Pressure: By reducing the pressure, the gas molecules are spread further apart. This increases the "mean free path" of electrons, allowing them to gain enough kinetic energy from an electric field to collide with gas molecules and knock off electrons (ionisation).
High Voltage: A high potential difference (voltage) is required to provide the strong electric field necessary to accelerate these electrons and maintain the flow of current through the gas.
Step-by-Step Solution
Identify the state of the gas: At high pressure, gas molecules are packed too closely, leading to frequent collisions that prevent electrons from gaining enough energy to ionise the gas. Therefore, high pressure is incorrect.
Evaluate the voltage: Low voltage is insufficient to overcome the ionisation energy of gas molecules. Therefore, low voltage is incorrect.
Combine the requirements: To facilitate a discharge (conduction), we need to reduce the density of the gas (low pressure) and apply a strong force to move the charges (high voltage).
Conclusion: Gases conduct electricity only when subjected to low pressure and high voltage. This is the principle behind devices like neon signs and fluorescent tubes.
Correct Option
Comparing this to your options, the correct condition is low pressure & high voltage.
Exam Tip: Think of a fluorescent tube in your classroom. It contains gas at low pressure, and the starter/ballast provides the high voltage "kick" needed to make the gas glow (conduct). This will help you remember that "Low Pressure + High Voltage = Light/Conduction."
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14.
The length of the seconds hand of laboratory clock is 0.1m. Calculate the speed at the top of the seconds hand
1. A.1.05 × 10 $^{-2}$ ms $^{-1}$
2. B.1.85 × 10 $^{-4}$ ms $^{-1}$
3. C.9.50 × 10 $^{-1}$ ms $^{-1}$
4. D.5.25 × 10 $^{-3}$ ms $^{-1}$
Show answer
Answer: A. 1.05 × 10 $^{-2}$ ms $^{-1}$
AI explanation
Analysis
To calculate the speed of the tip of the seconds hand, we need to treat the motion as circular motion. The seconds hand moves in a circle, and we are given the radius ( $r$ ) and the time it takes to complete one full revolution (the period, $T$ ).
Concept
The speed ( $v$ ) of an object moving in a circle is given by the formula:
$v = \frac{\text{distance}}{\text{time}} = \frac{2\pi r}{T}$
Where:
$r$ = radius (length of the seconds hand) = $0.1 \, \text{m}$
$T$ = period (time taken for the seconds hand to complete one full rotation) = $60 \, \text{seconds}$
$\pi$ $\approx 3.142$
Solution
Identify the variables: • $r = 0.1 \, \text{m}$ • $T = 60 \, \text{s}$
Apply the formula: $ $v = \frac{2 \times 3.142 \times 0.1}{60}$ $
Calculate the numerator: $ $2 \times 3.142 \times 0.1 = 0.6284$ $
Divide by the period: $ $v = \frac{0.6284}{60}$ $ $ $v \approx 0.010473 \, \text{ms}^{-1}$ $
Convert to standard form: $ $0.010473 \approx 1.05 \times 10^{-2} \, \text{ms}^{-1}$ $
Conclusion
Comparing our result with the given options, we can see that our calculation matches option A.
Exam Tip
When dealing with clock problems in physics, always remember that the period ( $T$ ) depends on the hand in question:
Seconds hand: $T = 60 \, \text{s}$
Minute hand: $T = 60 \, \text{minutes} = 3600 \, \text{s}$
Hour hand: $T = 12 \, \text{hours} = 12 \times 3600 \, \text{s}$
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15.
Water and Kerosine are drawn respectively into the two limbs of a Hare's apparatus. The destiny of water is 1.0gcm $^{-3}$ and the density of kerosine is 0.80gcm $^{-3}$ . If the height of the water column is 20.0cm, calculate the height of the kerosine column.
1. A.1.6cm
2. B.16.0cm
3. C.20.0cm
4. D.25.0cm
Show answer
Answer: D. 25.0cm
AI explanation
Analysis
This problem involves the principle of a Hare's apparatus, which is used to compare the densities of two liquids. In this apparatus, the pressure exerted by the column of liquid in each limb must be equal at the level of the common interface (the bottom).
Concept
The pressure ( $P$ ) exerted by a liquid column is given by the formula:
$P = \rho gh$
Where:
$\rho$ (rho) = density of the liquid
$g$ = acceleration due to gravity
$h$ = height of the liquid column
Since both limbs are under the same atmospheric pressure and the pressure at the base of both columns is equal, we use the principle:
$\rho_w h_w = \rho_k h_k$
Where:
$\rho_w$ = density of water
$h_w$ = height of water
$\rho_k$ = density of kerosine
$h_k$ = height of kerosine
Solution
Step 1: Identify the given values.
Density of water ( $\rho_w$ ) = $1.0 \, \text{gcm}^{-3}$
Height of water ( $h_w$ ) = $20.0 \, \text{cm}$
Density of kerosine ( $\rho_k$ ) = $0.80 \, \text{gcm}^{-3}$
Height of kerosine ( $h_k$ ) = ?
Step 2: Substitute the values into the formula.
$1.0 \times 20.0 = 0.80 \times h_k$
$20.0 = 0.80 \times h_k$
Step 3: Solve for $h_k$ .
$h_k = \frac{20.0}{0.80}$
$h_k = \frac{200}{8}$
$h_k = 25.0 \, \text{cm}$
Conclusion
The height of the kerosine column is 25.0 cm.
Exam Tip
Always remember that in a Hare's apparatus, the liquid with the lower density must have a higher column to balance the pressure of the denser liquid. Since kerosine is less dense than water ( $0.8 < 1.0$ ), you should expect your answer to be greater than 20.0 cm. If you get a smaller number, check your calculation!
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16.
In Sunlight, a blue flower looks blue because we see the flower by the light it
1. A.receives from our eyes
2. B.disperses
3. C.absorbed
4. D.reflect
Show answer
Answer: D. reflect
AI explanation
1. Analyze the question
The question asks why a blue flower appears blue when viewed in sunlight. We need to understand how objects interact with light to produce the colors we perceive.
2. Explain the concept
When white light (which contains all the colors of the visible spectrum: ROYGBIV) hits an object, three things can happen to the light:
Absorption: The object takes in the energy of the light waves.
Transmission: The light passes through the object (like glass).
Reflection: The light bounces off the surface of the object.
The color we see an object as is determined by the wavelength of the light that is reflected into our eyes. An object appears blue because it absorbs all other colors in the white light spectrum and reflects only the blue light back to our eyes.
3. Show the solution
Step 1: Sunlight is "white light," meaning it contains all colors (Red, Orange, Yellow, Green, Blue, Indigo, Violet).
Step 2: When this white light hits a blue flower, the pigments in the flower absorb the energy of the red, yellow, green, and other wavelengths.
Step 3: The blue wavelength is not absorbed; instead, it is reflected off the surface of the petals.
Step 4: This reflected blue light travels to our eyes, which is why our brain interprets the flower as "blue."
4. Identify the answer
Looking at the options provided:
A is incorrect because we do not see by light coming from our eyes.
B is incorrect because dispersion is the splitting of light (like in a prism), not the cause of object color.
C is incorrect because if the flower absorbed blue light, it would appear black (the absence of reflected light).
D is correct because the flower reflects the blue light to our eyes.
(Note: While the option is written as "reflect" in your list, grammatically it should be "reflects," but it is clearly the intended correct answer.)
5. Tip
Memory Trick: Think of color as a "rejection." An object is the color of the light it rejects (reflects). If you wear a red shirt, it is because the shirt is "rejecting" red light and keeping all the other colors for itself!
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17.
The diagram shows a uniform meter rule AB which balances horizontally at the 90cm mark when a mass of 0.2kg is suspended from B. Calculate the mass of the meter rule.
1. A.0.05kg
2. B.0.20kg
3. C.0.80kg
4. D.1.00kg
Show answer
Answer: A. 0.05kg
AI explanation
Analysis
To solve this problem, we apply the Principle of Moments. For a body to be in equilibrium, the sum of the clockwise moments about a pivot must equal the sum of the anticlockwise moments about the same pivot.
Concept
The Pivot: The meter rule is balanced at the 90cm mark.
Center of Gravity: For a uniform meter rule, the weight acts at its geometric center, which is the 50cm mark.
The Forces: • Weight of the rule ( $W_r$ ): Acts downwards at the 50cm mark. • Weight of the suspended mass ( $W_m$ ): Acts downwards at the 100cm mark (point B).
Distances from the pivot (90cm): • Distance of the rule's weight from the pivot = $90\text{cm} - 50\text{cm} = 40\text{cm}$ . • Distance of the suspended mass from the pivot = $100\text{cm} - 90\text{cm} = 10\text{cm}$ .
Step-by-Step Solution
Let $M$ be the mass of the meter rule. The weight of the rule is $M \times g$ (where $g$ is acceleration due to gravity). The weight of the suspended mass is $0.2\text{kg} \times g$ .
Applying the Principle of Moments:
$\text{Clockwise Moment} = \text{Anticlockwise Moment}$
$(M \times g) \times (\text{distance from pivot}) = (\text{Mass of load} \times g) \times (\text{distance from pivot})$
Since the rule is balanced at 90cm:
The weight of the rule ( $Mg$ ) acts at 50cm, creating an anticlockwise moment about the 90cm pivot.
The mass at B (0.2kg) acts at 100cm, creating a clockwise moment about the 90cm pivot.
$M \times g \times (90 - 50) = 0.2 \times g \times (100 - 90)$
$M \times 40 = 0.2 \times 10$
$40M = 2$
$M = \frac{2}{40}$
$M = 0.05\text{kg}$
Conclusion
The mass of the meter rule is 0.05kg.
Exam Tip
When dealing with "uniform" objects in physics, always remember that the weight acts exactly at the midpoint (50cm for a meter rule). If the question says "non-uniform," the center of gravity will be given or must be calculated. Always draw a quick sketch of the rule and label your pivot and distances to avoid mixing up your clockwise and anticlockwise sides!
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18.
The pitch of a screw jack is 0.45cm and the arm is 60cm long. If the efficiency of the Jack is 75/π %, calculate the mechanical advantage.
1. A.400
2. B.300
3. C.200
4. D.150
Show answer
Answer: C. 200
AI explanation
1. Analyze the Question
We are given:
Pitch ( $p$ ): $0.45\text{ cm}$
Length of arm ( $R$ ): $60\text{ cm}$
Efficiency ( $\eta$ ): $\frac{75}{\pi}\%$
Goal: Calculate the Mechanical Advantage (M.A.)
2. Explain the Concept
A screw jack is a simple machine. To solve this, we need two key formulas:
Velocity Ratio (V.R.) of a screw jack: $V.R. = \frac{2\pi R}{p}$ , where $R$ is the length of the arm and $p$ is the pitch.
Efficiency ( $\eta$ ): $\eta = \frac{M.A.}{V.R.} \times 100\%$ . • Note: Since the efficiency is given as a fraction involving $\pi$ , we will express the percentage as a decimal: $\eta = \frac{75}{\pi} \div 100 = \frac{75}{100\pi} = \frac{3}{4\pi}$ .
3. Show the Solution
Step 1: Calculate the Velocity Ratio (V.R.)
$V.R. = \frac{2 \times \pi \times 60}{0.45}$
$V.R. = \frac{120\pi}{0.45}$
To simplify, multiply the numerator and denominator by 100:
$V.R. = \frac{12000\pi}{45} = \frac{800\pi}{3}$
Step 2: Calculate the Mechanical Advantage (M.A.) Using the efficiency formula:
$\eta = \frac{M.A.}{V.R.}$
$\frac{3}{4\pi} = \frac{M.A.}{\frac{800\pi}{3}}$
Now, solve for M.A.:
$M.A. = \frac{3}{4\pi} \times \frac{800\pi}{3}$
The $3$ s cancel out, and the $\pi$ s cancel out:
$M.A. = \frac{800}{4}$
$M.A. = 200$
4. Identify the Answer
Comparing our result to the options provided: A. 400 B. 300 C. 200 D. 150
The calculated value matches option C.
5. Exam Tip
When dealing with circular motion in machines (like screw jacks or wheel and axles), always remember that the distance moved by the effort in one full rotation is the circumference of the circle described by the arm ( $2\pi R$ ). If you see $\pi$ in the efficiency percentage, it is almost certainly there to cancel out the $\pi$ in your Velocity Ratio calculation—don't let it panic you!
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19.
Which of the following statements is/are correct for a freely falling body? I. the total is entirely kinetic II. the ratio of potential energy to kinetic energy is constant III. the sum of potential and kinetic energy is constant
1. A.I only
2. B.II only
3. C.III only
4. D.I & III only
Show answer
Answer: C. III only
AI explanation
Analysis of the Question
This question tests your understanding of the Law of Conservation of Mechanical Energy as it applies to a body in free fall (ignoring air resistance). We need to evaluate three statements regarding the energy transformations of a falling object.
Concept Explanation
When an object falls freely under gravity:
Potential Energy (PE): As the object falls, its height ( $h$ ) decreases, so its potential energy ( $PE = mgh$ ) decreases.
Kinetic Energy (KE): As the object falls, its velocity ( $v$ ) increases, so its kinetic energy ( $KE = \frac{1}{2}mv^2$ ) increases.
Total Mechanical Energy (TME): According to the Law of Conservation of Energy, the total mechanical energy ( $TME = PE + KE$ ) remains constant throughout the fall, provided there is no air resistance.
Step-by-Step Evaluation
Statement I: "The total is entirely kinetic." This is incorrect. At the start of the fall, the body has maximum potential energy and zero kinetic energy. During the fall, it has a combination of both. It only becomes "entirely kinetic" at the very instant it hits the ground. Therefore, this statement is not true for the entire duration of the fall.
Statement II: "The ratio of potential energy to kinetic energy is constant." This is incorrect. Since $PE$ is decreasing and $KE$ is increasing, the ratio $\frac{PE}{KE}$ is constantly changing as the object falls.
Statement III: "The sum of potential and kinetic energy is constant." This is correct. This is the definition of the Principle of Conservation of Mechanical Energy. As $PE$ is lost, an equal amount of $KE$ is gained, keeping the total sum constant.
Conclusion
Since only Statement III is correct, the correct option is C.
Exam Tip: Whenever you see questions about "freely falling bodies" in JAMB Physics, always remember that Total Energy is conserved. If the question mentions air resistance, the total mechanical energy would decrease because some energy is converted into heat, but in standard JAMB problems, we assume a vacuum unless stated otherwise.
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20.
In a slide wire bridge, the balance is obtained at a point 25cm from one end of wire 1m long. The resistance to be tested is connected to that end and a standard resistance of 3.6 $\Omega$ is connected to the other end of the wire. Determine the value of the unknown resistance
1. A.3.2 $\Omega$
2. B.1.4 $\Omega$
3. C.3.21 $\Omega$
4. D.1.2 $\Omega$
Show answer
Answer: D. 1.2 $\Omega$
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21.
Which of these is observed when air is pumped out of a discharge tube without lowering its pressure
1. A.the conductivity of the air increases
2. B.the conductivity of the air decreases
3. C.conduction does not occur
4. D.spark are produced
Show answer
Answer: D. spark are produced
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22.
If the attraction of the sun is suddenly ceased, the earth would continue to move in a straight line making a tangent with the original orbit. This statement is derived from Newton's
1. A.First law of motion
2. B.Second law of motion
3. C.Third law of motion
4. D.Law of universal gravitation
Show answer
Answer: A. First law of motion
AI explanation
Analysis of the Question
The question asks us to identify the specific law of motion that explains why an object (the Earth) would continue moving in a straight line if the external force (the Sun's gravitational pull) acting upon it were suddenly removed.
Concept Explanation
To solve this, we must look at Newton’s Laws of Motion:
Newton’s First Law (Law of Inertia): This law states that an object will remain at rest or continue to move at a constant velocity in a straight line unless acted upon by an external force. Inertia is the property of matter that resists a change in its state of motion.
Newton’s Second Law: This law relates force, mass, and acceleration ( $F = ma$ ). It explains what happens when an external force is applied.
Newton’s Third Law: This law states that for every action, there is an equal and opposite reaction.
In the Earth's orbit, the Sun's gravitational force acts as a centripetal force, constantly pulling the Earth toward the center and forcing it to move in a circular path. If that force ceases, there is no longer a net force to pull the Earth out of its straight-line path. According to the First Law, the Earth will simply continue moving in the direction it was headed at the exact moment the force vanished—which is along the tangent to its orbit.
Step-by-Step Solution
Identify the state of motion: The Earth is currently in a state of uniform circular motion due to the Sun's gravity.
Identify the change: The "attraction of the sun" (the external force) is removed.
Apply the law: According to Newton's First Law, an object in motion stays in motion in a straight line unless an external force changes that state. Without the gravitational force, there is no longer a "change" in direction (acceleration).
Conclusion: The Earth will follow the path of its instantaneous velocity, which is a straight line tangent to the orbit. This is a classic demonstration of the Law of Inertia.
Correct Answer
The statement is derived from Newton's First Law of Motion.
Exam Tip
Whenever you see a question about an object "continuing its state" or "moving in a straight line" when forces are removed or balanced, immediately think of Newton's First Law (Inertia). It is the law that defines the natural tendency of objects to keep doing exactly what they are already doing!
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23.
The part of the human eye that does similar work as the diaphragm of a camera lens is the
1. A.Ciliary muscles
2. B.Pupil
3. C.Iris
4. D.Retina
Show answer
Answer: C. Iris
AI explanation
Analysis
The question asks us to identify the part of the human eye that functions like the diaphragm of a camera. To solve this, we need to understand the function of a camera diaphragm and compare it to the structures of the human eye.
Concept Explanation
The Camera Diaphragm: In a camera, the diaphragm is an adjustable opening (aperture) that controls the amount of light entering the camera lens. When it is bright, the diaphragm closes to let in less light; when it is dim, it opens wider to let in more light.
The Iris: In the human eye, the iris is the colored part of the eye. It contains muscles that control the size of the pupil. By expanding or contracting, the iris regulates the amount of light that enters the eye, performing the exact same function as the camera diaphragm.
The Pupil: This is the hole or opening itself (the aperture), not the mechanism that controls the size of the opening.
The Ciliary Muscles: These control the shape of the eye lens to focus on objects at different distances (accommodation), not the amount of light.
The Retina: This acts like the camera's film or sensor, where the image is formed.
Step-by-Step Solution
Identify the function: We are looking for the part that regulates light intensity.
Evaluate the options: • Ciliary muscles: Responsible for focusing (accommodation). • Pupil: The aperture itself, not the control mechanism. • Iris: The muscular ring that adjusts the size of the pupil to control light entry. • Retina: The light-sensitive screen where the image is captured.
Conclusion: Since the iris acts as the adjustable shutter/diaphragm that controls the size of the pupil, it is the correct anatomical equivalent to the camera diaphragm.
Identifying the Answer
This aligns with our biological understanding of the eye's anatomy.
Exam Tip
Think of the eye as a camera:
Iris = Diaphragm (controls light).
Pupil = Aperture (the hole).
Lens = Camera Lens (focusing).
Retina = Film/Sensor (image capture).
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24.
A rectangular solid block has length 10cm, breadth 5cm and height 2cm. If it lies on a horizontal surface, and has density 100kg/m $^3$ , calculate the pressure it exerts on the surface.
1. A.20 N/m $^2$
2. B.100 N/m $^2$
3. C.400 N/m $^2$
4. D.300 N/m $^2$
Show answer
Answer: A. 20 N/m $^2$
AI explanation
1. Analyze the question
We are given the dimensions of a rectangular block (length, breadth, and height) and its density. We need to calculate the pressure it exerts on a horizontal surface.
Given:
Length ( $l$ ) = 10 cm = 0.1 m
Breadth ( $b$ ) = 5 cm = 0.05 m
Height ( $h$ ) = 2 cm = 0.02 m
Density ( $\rho$ ) = 100 kg/m³
Acceleration due to gravity ( $g$ ) = 10 m/s² (standard value used in JAMB)
2. Explain the concept
Pressure ( $P$ ): Defined as Force per unit area ( $P = \frac{F}{A}$ ).
Force ( $F$ ): In this case, the force is the weight of the block ( $F = mg$ ).
Mass ( $m$ ): Calculated as Density $\times$ Volume ( $m = \rho \times V$ ).
Volume ( $V$ ): $l \times b \times h$ .
Area ( $A$ ): The surface area in contact with the ground is $l \times b$ .
Shortcut Formula: For a solid block of uniform density, the pressure exerted on the surface it rests on can be simplified: $P = \frac{mg}{A} = \frac{(\rho \times V) \times g}{A} = \frac{\rho \times (l \times b \times h) \times g}{l \times b}$ The $(l \times b)$ cancels out, leaving: $P = \rho \times h \times g$
3. Show the solution
Using the simplified formula: $P = \rho \times h \times g$
$\rho = 100 \text{ kg/m}^3$
$h = 0.02 \text{ m}$
$g = 10 \text{ m/s}^2$
$P = 100 \times 0.02 \times 10$ $P = 100 \times 0.2$ $P = 20 \text{ N/m}^2$
4. Identify the answer
The calculated pressure is 20 N/m². This matches Option A.
5. Tip
When calculating pressure for a solid block, you don't always need to calculate the total mass and total area separately. If the block is uniform, the pressure is simply the product of its density, its height, and gravity ( $P = \rho gh$ ). This is the same formula used for liquid pressure! Always ensure your units are in SI (meters, kilograms, seconds) before calculating.
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25.
The lower fixed part of a faulty thermometer reads 2°C while the upper fixed point is 100°C. What is the true temperature when the thermometer reads 51°C?
1. A.52°C
2. B.50°C
3. C.49°C
4. D.46°C
Show answer
Answer: B. 50°C
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26.
When two objects A and B are supplied with the same quantity of heat, the temperature change in A is obtained to be twice that of B. The mass of A is half that of B. The ratio of the specific heat capacity of A to B is
1. A.1 : 4
2. B.4 : 1
3. C.1 : 1
4. D.2 : 1
Show answer
Answer: C. 1 : 1
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27.
A man on a bench will exert the greatest pressure on the bench when he
1. A.lies flat on his back
2. B.lies flat on his belly
3. C.stands on both feet
4. D.stands on the toes of one foot
Show answer
Answer: D. stands on the toes of one foot
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28.
A projectile of mass 4kg is fired vertically and reaches a maximum height of 40m. Calculate the potential energy at the highest point (g = 10ms $^{-2}$
1. A.1800J
2. B.1600J
3. C.600J
4. D.440J
Show answer
Answer: B. 1600J
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29.
A siren having a ring of 200 hole makes 132 rev/min. A jet of air is directed on the set of holes. Calculate the frequency and wavelength in air of the note produced (take v = 350m/s)
1. A.0.795m
2. B.0.625m
3. C.0.335m
4. D.0.125m
Show answer
Answer: A. 0.795m
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30.
According to kinetic molecular model, in gases
1. A.The molecule are very fast apart & occupy all the space made available
2. B.The particles occur in clusters with molecules slightly farther apart
3. C.The particles vibrate about fixed positions and are held together by the strong intermolecular bond between them
4. D.The particles are closely packed together, they occupy minimum space & are usually arranged in a regular pattern
Show answer
Answer: A. The molecule are very fast apart & occupy all the space made available
AI explanation
Analysis
This question tests your understanding of the Kinetic Molecular Theory of Matter, which describes how particles behave in different states of matter (solids, liquids, and gases). We need to identify the specific behavior of gas molecules.
Concept Explanation
The Kinetic Molecular Theory states that matter is made up of tiny particles that are in constant motion. The state of matter depends on the energy of these particles and the strength of the forces holding them together:
Solids: Particles are closely packed in a fixed, regular pattern. They vibrate about fixed positions because intermolecular forces are very strong. (This matches Option D).
Liquids: Particles are close together but can slide past one another. They have more energy than solids but are still held together by moderate intermolecular forces. (This matches Option B).
Gases: Particles have very high kinetic energy. They are far apart, move randomly at high speeds, and have negligible intermolecular forces. Because they move randomly and are not held together, they expand to fill the entire volume of any container they are placed in.
Step-by-Step Solution
Evaluate Option D: This describes a solid. The particles are packed in a regular pattern.
Evaluate Option C: This also describes a solid. The mention of "vibrating about fixed positions" is a classic characteristic of solid-state particles.
Evaluate Option B: This describes a liquid. Particles in liquids are closer together than in gases and often form temporary clusters.
Evaluate Option A: This describes a gas. Because gas molecules have high kinetic energy and weak intermolecular forces, they spread out as far as possible, filling all available space.
Conclusion
Based on the kinetic molecular model, gases are characterized by large distances between molecules and their ability to expand to fill any container. Therefore, Option A is the correct description.
Exam Tip: When you see questions about states of matter, remember the "Energy vs. Order" rule:
Solids = Low energy, High order (Fixed).
Gases = High energy, Low order (Random/Spread out).
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31.
A straight wire 15cm long, carrying a current of 6.0A is in a uniform field of 0.40T. What is the force on the wire when it is at right angle to the field
1. A.0.46N
2. B.0.35N
3. C.0.36N
4. D.0,24N
Show answer
Answer: C. 0.36N
AI explanation
1. Analyze the question
We are given a current-carrying wire placed in a uniform magnetic field. We need to calculate the magnetic force acting on the wire.
Length ( $L$ ): 15 cm
Current ( $I$ ): 6.0 A
Magnetic Flux Density ( $B$ ): 0.40 T
Angle ( $\theta$ ): 90° (since it is at a "right angle" to the field)
2. Explain the concept
The force ( $F$ ) on a current-carrying conductor in a magnetic field is given by the formula:
$F = BIL \sin(\theta)$
Where:
$B$ is the magnetic flux density (measured in Tesla, T).
$I$ is the current (measured in Amperes, A).
$L$ is the length of the wire (must be in meters, m).
$\theta$ is the angle between the wire and the magnetic field.
Important: Always ensure your length is in SI units (meters) before calculating.
3. Show the solution
Step 1: Convert units The length is given in centimeters. We must convert it to meters:
$L = 15\text{ cm} = \frac{15}{100}\text{ m} = 0.15\text{ m}$
Step 2: Apply the formula Since $\theta = 90^\circ$ , we know that $\sin(90^\circ) = 1$ .
$F = B \times I \times L \times \sin(90^\circ)$
$F = 0.40 \times 6.0 \times 0.15 \times 1$
Step 3: Calculate
$F = 0.40 \times 6.0 = 2.4$
$F = 2.4 \times 0.15$
$F = 0.36\text{ N}$
4. Identify the answer
Comparing our result to the given options: A. 0.46N B. 0.35N C. 0.36N D. 0.24N
The calculated force is 0.36N, which matches option C.
5. Exam Tip
In JAMB Physics, always watch out for unit conversions! Many students lose marks because they calculate using centimeters instead of converting to meters. A quick way to remember the formula is "BIL-sin-theta." Also, remember that $\sin(90^\circ)$ is 1, which is the maximum force possible for a wire in a magnetic field.
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32.
A body was slightly displaced from its equilibrium position. Which one of the following is a condition for its stable equilibrium
1. A.an increase in the kinetic energy of the body
2. B.an increase in the potential energy of the body
3. C.a decrease in the kinetic energy of the body
4. D.an increase in the height of the body
Show answer
Answer: B. an increase in the potential energy of the body
AI explanation
Analysis
The question asks for the condition that defines stable equilibrium when a body is slightly displaced from its original position.
Concept Explanation
Equilibrium occurs when the net force acting on a body is zero. However, there are three types of equilibrium based on how the body reacts to a displacement:
Stable Equilibrium: When a body is slightly displaced and released, it tends to return to its original position. In this state, the body's potential energy is at a minimum. When you displace it, you are essentially "lifting" it against gravity or a restoring force, which causes its potential energy to increase. Because the system naturally wants to return to the lowest energy state, it moves back to its original position.
Unstable Equilibrium: When a body is slightly displaced and moves further away from its original position. Here, the potential energy is at a maximum.
Neutral Equilibrium: When a body is displaced and stays in its new position. The potential energy remains constant.
Step-by-Step Solution
Identify the state: We are looking for stable equilibrium.
Analyze the energy change: When a body in stable equilibrium (like a ball at the bottom of a bowl) is pushed slightly, it rises to a higher position.
Relate to Potential Energy ( $PE = mgh$ ): As the body rises, its height ( $h$ ) increases. Since potential energy is directly proportional to height, the potential energy of the body must increase.
Conclusion: The increase in potential energy creates a "restoring force" that pulls the body back down to the point of minimum potential energy (the equilibrium position).
Identifying the Answer
Option A and C (Kinetic Energy) are incorrect because kinetic energy relates to motion, not the stability of the position.
Option D (Increase in height) is a consequence of the displacement, but the fundamental physical condition that defines the stability is the increase in potential energy.
Option B is the correct scientific description of the state of the body after displacement.
Exam Tip
Think of a ball in a bowl:
Stable: Ball at the bottom. If you push it, it goes up (Potential Energy increases) and rolls back down.
Unstable: Ball balanced on top of an inverted bowl. If you push it, it falls away (Potential Energy decreases).
Neutral: Ball on a flat table. It just stays wherever you push it.
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33.
When blue and green colours of light are mixed, the resultant colour is
1. A.cyan
2. B.magenta
3. C.black
4. D.yellow
Show answer
Answer: A. cyan
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34.
A metal rod has a length of 100cm at 200 $^oC$ . At what temperature will its length be 99.4cm. If the linear expansivity of the material of the rod is 2 x 10 $^{-5}C^{-1}$
1. A.200 $^o$ C
2. B.300 $^o$ C
3. C.100 $^o$ C
4. D.-100 $^o$ C
Show answer
Answer: D. -100 $^o$ C
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35.
Workdone on an object to bring it to a certain point in space is called
1. A.Gravitational potential energy
2. B.Potential energy
3. C.Kinetic energy
4. D.Mechanical energy
Show answer
Answer: A. Gravitational potential energy
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36.
Radio waves belongs to the class of waves whose velocity is about
1. A.340m/s
2. B.3 × 10 $^{6}$ m/s
3. C.3 × 10 $^{8}$ m/s
4. D.3 × 10 $^{-8}$ m/s
Show answer
Answer: C. 3 × 10 $^{8}$ m/s
AI explanation
1. Analyze the question
The question asks for the velocity of radio waves. In physics, radio waves are a specific type of wave within the electromagnetic spectrum. To answer this, we need to identify the speed at which all electromagnetic waves travel through a vacuum.
2. Explain the concept
Radio waves, along with light, X-rays, microwaves, and gamma rays, are electromagnetic waves. A fundamental principle in physics is that all electromagnetic waves travel at the same constant speed in a vacuum (or approximately the same speed in air). This speed is known as the speed of light, denoted by the symbol $c$ .
The value of this constant is approximately $300,000,000$ meters per second, which is written in standard form as $3 \times 10^8 \text{ m/s}$ .
3. Show the solution
Step 1: Identify the nature of the wave. Radio waves are electromagnetic waves.
Step 2: Recall the speed of electromagnetic waves. The speed of electromagnetic waves in a vacuum is a universal constant: $c \approx 3 \times 10^8 \text{ m/s}$ .
Step 3: Compare this with the given options: • A: $340 \text{ m/s}$ is the approximate speed of sound in air. • B: $3 \times 10^6 \text{ m/s}$ is incorrect. • C: $3 \times 10^8 \text{ m/s}$ matches the speed of light. • D: $3 \times 10^{-8} \text{ m/s}$ is an extremely slow speed, not applicable here.
4. Identify the answer
The correct option is C.
5. Exam Tip
Remember the acronym "R-M-I-V-U-X-G" for the electromagnetic spectrum (Radio, Microwave, Infrared, Visible light, Ultraviolet, X-ray, Gamma ray). All of these travel at the speed of light ( $3 \times 10^8 \text{ m/s}$ ). Do not confuse this with the speed of sound ( $340 \text{ m/s}$ ), which is much slower and requires a medium to travel!
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37.
A coil X is moved quickly away from the end Y of a stationary metal bar and a current then flows in X as shown above. Then
1. A.the bar is not a magnet
2. B.Y is a north pole
3. C.Y is a South pole
4. D.Y repels coil X
Show answer
Answer: A. the bar is not a magnet
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38.
Which of the following statements are correct of the production and propagation of waves? I. vibration produces waves II. waves transmit energy along the medium III. the medium through which the wave travels does not travel with the wave IV. waves do not require any medium for transmission
1. A.I & IV only
2. B.II & IV only
3. C.III & IV only
4. D.I, II and III only
Show answer
Answer: D. I, II and III only
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39.
A cone is in unstable equilibrium, has its potential energy
1. A.decreased
2. B.increased
3. C.unchanged
4. D.oscillating
Show answer
Answer: A. decreased
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40.
Which of the following bodies, each with centre of gravity G, lying on a horizontal table, is/are in unstable equilibrium?
1. A.II only
2. B.III only
3. C.I & IV only
4. D.II & III only
Show answer
Answer: D. II & III only
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41.
The following are parts of the eye I. Retina II. Pupil III. Iris The correct equivalent in the camera in the same order are
1. A.Diaphragm, Aperture, film
2. B.Aperture, Diaphragm, Film
3. C.Film, Diaphragm, Aperture
4. D.Film, Aperture, Diaphragm
Show answer
Answer: D. Film, Aperture, Diaphragm
AI explanation
Analysis
To solve this question, we need to compare the biological structures of the human eye with the mechanical components of a camera. Both systems function on the principle of capturing light to form an image.
Concept Explanation
Retina: In the eye, the retina is the light-sensitive layer at the back where the image is formed. In a camera, the film (or the digital sensor) serves this exact purpose.
Pupil: The pupil is the opening in the center of the iris through which light enters the eye. In a camera, the corresponding opening that allows light to pass through is called the aperture.
Iris: The iris is the colored part of the eye that controls the size of the pupil, thereby regulating the amount of light entering the eye. In a camera, the diaphragm (or iris diaphragm) is the adjustable mechanism that controls the size of the aperture.
Step-by-Step Solution
Match I (Retina): The retina is the screen where the image is captured. The equivalent in a camera is the Film.
Match II (Pupil): The pupil is the hole/opening for light. The equivalent in a camera is the Aperture.
Match III (Iris): The iris controls the size of the opening. The equivalent in a camera is the Diaphragm.
Following the order given in the question (Retina, Pupil, Iris), the corresponding camera parts are: Film, Aperture, Diaphragm.
Comparing this to the options provided:
A: Diaphragm, Aperture, Film (Incorrect)
B: Aperture, Diaphragm, Film (Incorrect)
C: Film, Diaphragm, Aperture (Incorrect)
D: Film, Aperture, Diaphragm (Correct)
Exam Tip
Think of the Iris as the Diaphragm because they both act like a "curtain" or "shutter" that adjusts size. The Pupil is just the "hole" (Aperture) created by that curtain. Remembering that the Retina is the "Film" is usually the easiest part to start with!
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42.
The height at which the atmosphere ceases to exist is about 80km. If the atmospheric pressure on the ground level is 760mmHg, the pressure at a height of 20km above the ground level is (ρm = 13.6g/cm $^3$ ρ = 0.00013g/cm $^3$ )
1. A.380mmHg
2. B.570mmHg
3. C.190mmHg
4. D.480mmHg
Show answer
Answer: B. 570mmHg
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43.
The angular dispersion of a prism depends on
1. A.The index of refraction only
2. B.The angle of incidence as well as the index of refraction
3. C.The angle of incidence only
4. D.The thickness of the prism only
Show answer
Answer: B. The angle of incidence as well as the index of refraction
AI explanation
Analysis
The question asks for the factors that determine the angular dispersion of a prism. Angular dispersion is the difference in the angle of deviation between the extreme colors (usually red and violet) of a spectrum produced by a prism.
Concept Explanation
When white light passes through a prism, it splits into its constituent colors because the refractive index ( $n$ ) of the glass varies with the wavelength of light. This phenomenon is called dispersion.
The angular dispersion ( $\theta$ ) is given by the formula:
$\theta = \delta_v - \delta_r$
Where:
$\delta_v$ is the angle of deviation for violet light.
$\delta_r$ is the angle of deviation for red light.
For a thin prism, the angle of deviation ( $\delta$ ) is calculated as:
$\delta = A(n - 1)$
Where:
$A$ is the refracting angle of the prism.
$n$ is the refractive index of the material.
However, for a prism in a general state (not necessarily thin), the deviation depends on the angle of incidence ( $i$ ), the refracting angle of the prism ( $A$ ), and the refractive index ( $n$ ) of the material. Since the dispersion is the difference in deviations for different wavelengths, it is fundamentally dependent on how the refractive index changes with wavelength and the geometry of the light's path through the prism, which is dictated by the angle of incidence.
Step-by-Step Solution
Refractive Index: The refractive index ( $n$ ) determines how much each color is bent. Since different colors have different refractive indices in the same medium, this is the primary cause of dispersion.
Angle of Incidence: The path the light takes through the prism is determined by the angle of incidence. If the angle of incidence changes, the deviation of the light rays changes. Consequently, the difference between the deviations of the extreme colors (the angular dispersion) is also affected by the angle of incidence.
Conclusion: Because the deviation of light rays is a function of both the material's properties (refractive index) and the orientation of the light entering the prism (angle of incidence), the angular dispersion depends on both.
Identifying the Answer
This is because the deviation of light through a prism is not constant; it varies with the angle of incidence, and therefore the spread (dispersion) between the colors is also dependent on the angle at which the light enters the prism.
Exam Tip
When dealing with prism questions, always remember the mnemonic "D-I-A": Deviation depends on the Degree of incidence (angle of incidence), the Index of refraction, and the Angle of the prism. If you are asked about dispersion, remember that it is simply the difference in deviation for two different wavelengths, so it inherits these dependencies!
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44.
A well 1km deep is filled with a liquid of density 950kg/m $^3$ and g = 10m/s $^2$ , the pressure at the bottom of the well is
1. A.9.6 × 10 $^6$ N/m $^2$
2. B.9.5 x 10 $^5$ N/m $^2$
3. C.9.4 x 10 $^6$ N/m $^2$
4. D.9.5 x 10 $^6$ N/m $^2$
Show answer
Answer: D. 9.5 x 10 $^6$ N/m $^2$
AI explanation
Analysis
To find the pressure at the bottom of a well filled with liquid, we need to calculate the hydrostatic pressure. This is the pressure exerted by a fluid at equilibrium at a given point within the fluid, due to the force of gravity.
Concept
The formula for hydrostatic pressure ( $P$ ) is:
$P = \rho gh$
Where:
$\rho$ (rho) = density of the liquid (in $kg/m^3$ )
$g$ = acceleration due to gravity (in $m/s^2$ )
$h$ = depth of the liquid (in meters)
Solution
Step 1: Identify the given values and ensure they are in SI units.
Depth ( $h$ ) = $1\text{ km} = 1,000\text{ m} = 10^3\text{ m}$
Density ( $\rho$ ) = $950\text{ kg/m}^3$
Gravity ( $g$ ) = $10\text{ m/s}^2$
Step 2: Substitute the values into the formula.
$P = 950 \times 10 \times 1,000$
Step 3: Perform the calculation.
$P = 950 \times 10,000$
$P = 9,500,000\text{ N/m}^2$
Step 4: Convert to standard form. To express $9,500,000$ in standard form, we move the decimal point 6 places to the left:
$P = 9.5 \times 10^6\text{ N/m}^2$
Conclusion
Comparing our result to the given options, we can see that our calculated value matches option D.
Exam Tip: Always check your units before calculating! JAMB often gives distances in kilometers (km) to test if you remember to convert them to meters (m). Also, remember that $10^6$ is a million; if you get a very large number, standard form is your best friend to avoid counting zeros incorrectly.
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45.
A train has an initial velocity of 44m/s and an acceleration of -4m/s $^2$ . Calculate its velocity after 10 seconds
1. A.10m/s
2. B.6m/s
3. C.8m/s
4. D.4m/s
Show answer
Answer: D. 4m/s
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46.
An alternating current can induce voltage because it has
1. A.ripple value
2. B.varying magnetic field
3. C.weaker magnetic field than direct current
4. D.high peak value
Show answer
Answer: B. varying magnetic field
AI explanation
1. Analyze the question
The question asks for the fundamental reason why an alternating current (AC) is capable of inducing a voltage in a nearby conductor or coil.
2. Explain the concept
This phenomenon is based on Faraday’s Law of Electromagnetic Induction. Faraday’s Law states that an electromotive force (EMF) or voltage is induced in a circuit whenever there is a change in the magnetic flux linked with that circuit.
Direct Current (DC): Flows in one constant direction. If the current is steady, it produces a constant magnetic field. A constant magnetic field does not change, so it cannot induce a voltage in a stationary secondary coil.
Alternating Current (AC): Constantly changes its magnitude and reverses its direction periodically. Because the current is always changing, the magnetic field it produces around the conductor is also constantly changing (varying). This changing magnetic field cuts across nearby conductors, satisfying the condition for electromagnetic induction.
3. Show the solution
Step 1: Identify the requirement for induction. According to Faraday's Law, $e = -N \frac{d\Phi}{dt}$ , where $e$ is the induced voltage and $\frac{d\Phi}{dt}$ is the rate of change of magnetic flux.
Step 2: Relate the current to the magnetic field. A current-carrying conductor creates a magnetic field ( $B$ ). For AC, $I = I_0 \sin(\omega t)$ , which means the magnetic field $B$ is also a function of time.
Step 3: Conclude the effect. Since the current varies with time, the magnetic field varies with time. This variation ( $\frac{dB}{dt}$ ) is what induces the voltage in a transformer or a secondary coil.
4. Identify the answer
Comparing this to the options:
A is incorrect because "ripple" refers to the fluctuations in rectified DC, not the fundamental cause of induction.
B is correct because the varying magnetic field is the direct physical mechanism that satisfies Faraday's Law.
C is incorrect because the strength of the field is not the primary factor; the change in the field is.
D is incorrect because peak value relates to amplitude, not the induction process itself.
5. Tip
Exam Strategy: Whenever you see a question about "induction" (transformers, generators, or induction coils), look for keywords like "changing," "varying," "cutting," or "rate of change." If the magnetic field isn't changing, no induction occurs!
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47.
When the downward current flows in a straight vertical conductor, the direction of its magnetic field at a point due north of the wire is?
1. A.Upward
2. B.North
3. C.South
4. D.West
Show answer
Answer: C. South
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48.
The pin-hole camera produces a less sharply defined image when the
1. A.pin-hole is larger
2. B.illumination is less
3. C.screen is further from the pin-hole
4. D.object is further from the pin-hole
Show answer
Answer: A. pin-hole is larger
AI explanation
Analysis
This question tests your understanding of the principles of light and image formation in a pin-hole camera. You are asked to identify the condition that causes the image to lose its sharpness (become blurred).
Concept Explanation
A pin-hole camera works on the principle of the rectilinear propagation of light (light travels in straight lines).
How it works: Light rays from an object pass through a tiny hole to form an inverted image on a screen.
The "Pin-hole" effect: For a sharp image, the hole must be very small (approaching a point source).
The problem with a large hole: If the pin-hole is made larger, each point on the object sends a "beam" of light through the hole rather than a single ray. This beam covers a larger area on the screen, causing the light from adjacent points on the object to overlap. This overlapping results in a blurred or "less sharply defined" image.
Step-by-Step Solution
Evaluate Option A: A larger pin-hole allows more light rays from different parts of the object to pass through and overlap on the screen, creating a blurred image. This matches the definition of "less sharply defined."
Evaluate Option B: Illumination (brightness) affects the intensity of the image, not its sharpness.
Evaluate Option C: Moving the screen further away increases the magnification of the image, but it does not inherently make it "less sharp" in the context of the pin-hole size.
Evaluate Option D: Moving the object further away changes the size of the image, but does not affect the sharpness caused by the aperture size.
Conclusion
The sharpness of an image in a pin-hole camera is inversely proportional to the size of the hole. As the hole gets larger, the image becomes more blurred. Therefore, the correct condition is that the pin-hole is larger.
Exam Tip: Always remember the "Small Hole, Sharp Image" rule. If you are ever asked how to make the image sharper, the answer is always to make the pin-hole smaller. Conversely, making the hole larger makes the image brighter but blurrier.
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49.
Which of the following equations is the correct definition of the reactance of an indicator L?
1. A.Reactance = (Amplitude of voltage) $\div$ (Amplitude of current)
2. B.Reactance = (Amplitude of voltage) x (Amplitude of current)
3. C.Reactance = (Amplitude of current) $^2$ $\div$ (Amplitude of voltage)
4. D.Reactance = (Amplitude of current) $^2$ $\div$ (Amplitude of voltage) $\frac{1}{2}$
Show answer
Answer: A. Reactance = (Amplitude of voltage) $\div$ (Amplitude of current)
AI explanation
1. Analyze the question
The question asks for the definition of the reactance ( $X_L$ ) of an inductor in an A.C. circuit. Reactance is essentially the "opposition" to the flow of alternating current caused by an inductor, measured in Ohms ( $\Omega$ ).
2. Explain the concept
In an A.C. circuit, Ohm's Law applies to components like resistors, capacitors, and inductors. For an inductor, the relationship between the voltage across it ( $V_L$ ) and the current flowing through it ( $I_L$ ) is governed by the inductive reactance ( $X_L$ ).
The formula for Ohm's Law in an A.C. circuit is:
$V = I \times Z$
Where $Z$ is the impedance (or reactance, in the case of a pure inductor). Therefore:
$X_L = \frac{V}{I}$
When dealing with A.C. signals, we often use the peak values (amplitudes) of the voltage ( $V_0$ ) and the current ( $I_0$ ). Thus, the inductive reactance is defined as the ratio of the amplitude of the voltage to the amplitude of the current.
3. Show the solution
Step 1: Identify the relationship between voltage and current for an inductor: $V_L = I_L \times X_L$ .
Step 2: Rearrange the formula to solve for reactance ( $X_L$ ): $X_L = \frac{V_L}{I_L}$ .
Step 3: Apply this to the amplitudes (peak values): $X_L = \frac{\text{Amplitude of Voltage}}{\text{Amplitude of Current}}$ .
Step 4: Compare this result with the given options. Option A matches this derivation perfectly.
4. Identify the answer
The correct definition is the ratio of the amplitude of the voltage to the amplitude of the current.
Correct Option: A
5. Tip
Remember the acronym "V-I-R" (or in this case, V-I-X). Whenever you are asked for resistance, reactance, or impedance, it is almost always Voltage divided by Current. If you ever forget the formula, just look at the units: Resistance/Reactance is in Ohms ( $\Omega$ ), Voltage is in Volts ( $V$ ), and Current is in Amperes ( $A$ ). Since $V = I \times R$ , then $R = V/I$ .
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50.
The conductivity of gases at low pressure can be termed as I. hot cathode emission II. thermo ionic emission III. cold cathode emission IV. Field emission
1. A.I & II
2. B.II & III
3. C.III & IV
4. D.IV & V
Show answer
Answer: C. III & IV
AI explanation
Analysis
The question asks us to identify the specific phenomena associated with the conduction of electricity through gases when the pressure is kept very low (often in discharge tubes).
Concept Explanation
When a gas is at low pressure, it becomes a conductor of electricity if a sufficiently high potential difference is applied across it. This process involves the ionization of gas molecules.
Cold Cathode Emission: In a gas discharge tube at low pressure, the cathode is not heated. Instead, positive ions from the ionized gas strike the cathode with high kinetic energy, knocking off electrons. This is known as secondary emission or cold cathode emission.
Field Emission: When a very strong electric field is applied, the field itself is strong enough to pull electrons out of the surface of the cathode. This is known as field emission (or auto-electronic emission).
Thermo-ionic emission and hot cathode emission (which are essentially the same thing) require the cathode to be heated to high temperatures to "boil off" electrons. These do not describe the standard conductivity of gases at low pressure in a cold discharge tube.
Step-by-Step Solution
Step 1: Evaluate the options provided. We are looking for the processes that allow current to flow in a gas discharge tube without external heating.
Step 2: Identify that "Cold cathode emission" (III) occurs because the cathode is not heated; it relies on ion bombardment.
Step 3: Identify that "Field emission" (IV) occurs because the high potential difference creates a strong electric field that extracts electrons.
Step 4: Compare these with the provided options. Since III and IV are the correct physical processes for this phenomenon, we look for the option containing both.
Conclusion
The conductivity of gases at low pressure is primarily driven by the extraction of electrons from the cathode via ion bombardment (cold cathode emission) and the influence of strong electric fields (field emission). Therefore, III and IV are the correct descriptions.
Exam Tip
Remember: "Cold" means no heat is applied to the cathode. If you see "low pressure gas discharge," think of processes that don't require a heating filament. If the question mentioned a "thermionic valve" or "vacuum tube," then you would look for "hot cathode" or "thermionic" emission.
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51.
The following are some units I. Ns II. Non III. Nm $^{-2}$ IV. J°K $^{-1}$ V. JKg $^{-1}$ What are the units of latent heat?
1. A.I
2. B.II
3. C.III
4. D.V
Show answer
Answer: D. V
AI explanation
1. Analyze the question
The question asks us to identify the correct SI unit for latent heat from the provided list.
2. Explain the concept
Latent heat is the quantity of heat required to change the state of a substance without changing its temperature. The formula for latent heat ( $L$ ) is:
$Q = mL$
Where:
$Q$ is the quantity of heat (measured in Joules, J)
$m$ is the mass of the substance (measured in kilograms, kg)
$L$ is the specific latent heat
To find the unit of $L$ , we rearrange the formula:
$L = \frac{Q}{m}$
Substituting the units:
$Unit = \frac{J}{kg} = Jkg^{-1}$
3. Show the solution
I. Ns: This is the unit for Impulse or Change in Momentum.
II. Nm: This is the unit for Torque or Work (Newton-meters).
III. Nm⁻²: This is the unit for Pressure or Stress (Pascals).
IV. J°K⁻¹: This is the unit for Heat Capacity.
V. Jkg⁻¹: This is the unit for Specific Latent Heat.
Comparing our derived unit ( $Jkg^{-1}$ ) with the list, it matches item V.
4. Identify the answer
5. Exam Tip
When dealing with "Specific" quantities in Physics (like Specific Heat Capacity or Specific Latent Heat), the unit almost always involves "per unit mass" ( $kg^{-1}$ ). If you ever forget the unit, just look at the formula: if it has mass in the denominator, your unit must have $kg^{-1}$ !
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2019 JAMB Physics Past Questions

Questions 1–51

1. Analyze the Question

2. Explain the Concept

3. Show the Solution

4. Identify the Answer

5. Tip

Analysis

Concept

Solution

Conclusion

Exam Tip

1. Analyze the question

2. Explain the concept

3. Show the solution

4. Identify the answer

5. Exam Tip

Analysis

Concept Explanation

Step-by-Step Solution

Conclusion

Analysis

Concept Explanation

Step-by-Step Solution

Exam Tip

Analysis

Concept

Solution

Conclusion

Analysis

Concept

Step-by-Step Solution

Conclusion

Exam Tip

Analysis of the Question

Explanation of the Concept

Step-by-Step Solution

Identifying the Answer

Exam Tip

1. Analyze the Question

2. Explain the Concept

3. Show the Solution

4. Identify the Answer

5. Exam Tip

Analysis of the Question

Concept Explanation

Step-by-Step Solution

Conclusion

Exam Tip

Analysis

Concept Explanation

Step-by-Step Solution

Correct Option

Analysis

Concept

Solution

Conclusion

Exam Tip

Analysis

Concept

Solution

Conclusion

Exam Tip

1. Analyze the question

2. Explain the concept

3. Show the solution

4. Identify the answer

5. Tip

Analysis

Concept

Step-by-Step Solution

Conclusion

Exam Tip

1. Analyze the Question

2. Explain the Concept

3. Show the Solution

4. Identify the Answer

5. Exam Tip

Analysis of the Question

Concept Explanation