1. Which of the following are examples of electromagnetic radiation?

(a) Gamma rays

(b) Sound waves

(c) Radio waves

(d) Water waves

(e) Visible light

2. The particle theory of light explains

(a) Diffraction of light around a sharp edge.

(b) Refraction of light at a boundary.

(c) The photoelectric effect.

(d) None of the above.

3. A light-year equals

(a) The time it takes light to travel from the sun to the earth.

(b) The distance from the sun to the earth.

(c) The distance to the nearest star other than the sun.

(d) The distance light travels in one earth year.

4. Light behaves

(a) As a massive particle.

(b) Always as a wave.

(c) Sometimes as a wave, sometimes as a particle.

(d) As none of the above.

5. Does the wavelength of light depend on its frequency? Explain.

6. How does the energy of a photon of light depend on its frequency?

7. How does the intensity of illumination depend on the distance from a source radiating uniformly in all directions?

8. In your own words, explain how the speed of light has been measured.