1. A polaroid produces a strong beam of light which is :

2. Images of a distant lamp seen through a fire cloth rotate on rotating the cloth. This is due to the phenomenon of:

3. A young's double slit experiment uses a monochromatic source. The shape of interference fringes formed on a screen is :

4. A monochromatic light is refracted from air into a glass of refractive index µ. The ratio of the wavelengths of the incident and the refracted waves is:

5. The focal length of the lens is 50 cm; then its power is:

6. In the above question, the number of the lens is:

7. The refractive index of diamond is about:

8. Two lenses having power +6 D and -4 D are placed in contact. The power of the combination is

9. Diffraction was discovered by :

10. The electromagnetic wave theory of light fails to explain :