NECO Physics Past Questions & CBT Practice

The phenomenon of photoelectric effect is used in the following EXCEPT

1. A.automatic doors
2. B.bugler alarm
3. C.electric fire alarm✓ Correct
4. D.sound production from film tracks
5. E.television cameras

Which of the following is used for shielding radioactive fallout?

1. A.Aluminum
2. B.Lead✓ Correct
3. C.Iron
4. D.Plastic
5. E.Wood

Which of the following is NOT a component of a slide projector?

1. A.Concave mirror
2. B.Condenser
3. C.Convex mirror✓ Correct
4. D.light source
5. E.Screen.

Calculate the heat energy lost when 10g of boiling water changes to ice at 0°C. [Specific latent heat of ice 336Jg-1 . Specific heat capacity of water 4.2Jg-1 K-1]

1. A.840J
2. B.3360J
3. C.3420J
4. D.4200J
5. E.7560J✓ Correct

The wave theory of light does not explain photoelectricity because

1. A.light waves carry little energy
2. B.particles cannot be emitted by waves
3. C.the frequency of light waves too high
4. D.there is a threshold wavelength for electron emission✓ Correct
5. E.the wavelength of Light waves is too short.

An atom radiates 1.5 × 10-19J when an electron jumps from one level to another. What is the wavelength of the emitted radiation? (Planck’s constant 6.6 × l0-34Js ; Speed of light in vacuum = 3.0 × 108$ms^{-1}$)

1. A.1.32 × 10-6m✓ Correct
2. B.2.97 × 10-6m
3. C.3.30 × 10-6m
4. D.6.82 × 10-6m
5. E.8.01 × 10m-6