A current of 0.5 A flows through a resistor when connected to a 40 V battery. How much energy is dispatched in 2 minutes?

1. Analyze the Question

We are given:

• Current ($I$) = 0.5 A
• Voltage ($V$) = 40 V
• Time ($t$) = 2 minutes
• We need to find the energy ($E$) dispatched (or dissipated) by the resistor.

2. Explain the Concept

In electricity, the energy ($E$) dissipated by a component is given by the formula:

• $V$ is the potential difference in Volts (V).
• $I$ is the current in Amperes (A).
• $t$ is the time in seconds (s).

Important Note: In physics calculations, time must always be converted to seconds to match the SI unit of energy (Joules).

3. Show the Solution

Step 1: Convert time to seconds. Since 1 minute = 60 seconds:

Step 2: Apply the formula.

Step 3: Calculate.

4. Identify the Answer

Comparing our result to the given options: A. 2400 J B. 9600 J C. 1500 J D. 1200 J

The calculated value matches option A.

5. Exam Tip

Always watch out for units in JAMB Physics! If the time is given in minutes or hours, convert it to seconds immediately before plugging it into your formula. Also, remember that $V \times I$ gives you Power ($P$) in Watts; so, you can also think of the formula as $E = P \times t$.