# Nature and Propagation of Light | Old is Gold | Class XII

__Nature and Propagation of Light__

**Short**

1. Differentiate between a plane wave front and a spherical wave front.

2. Which parameter of light does not change on refraction?

4. What is Huygens principle?

5. When monochromatic light incidents on a surface, the reflected and refracted wave will have same frequency. Why?

6. State Huygens principle. Does it apply to sound waves in air?

7. What is a wave front?

**Long**

1. State and explain Huygens principle. Use the principle to show that a plane wave front incident obliquely on a plane mirror is reflected as a plane wave front so that angle of incidence is equal to the angle of reflection.

2. Prove the law of reflection of light using the wave theory?

3. Define Huygen’s principle and prove Snell’s law by the help of wave theory of light. State and explain Huygen’s principle. Use the principle to show that a plane wave front incident obliquely on a plane reflecting surface is reflected as a plane wave front so that the angle of incidence is equal to the angle of reflection.

4. Describe Michelson’s method for the determination of speed of light. Write advantages of the method over Foucault’s method.

5. State and explain Huygen’s principle. Use the principle to show that a p lane wave incident obliquely on a plane mirror is reflected as a plane wave so that the angle of incidence is equal to the angle of reflection.

6. Describe Foucault’s method for the determination of speed of light.