Chapter 10 Solutions — Wave Optics

Exercises

1. 1.
   Monochromatic light of wavelength 589 nm is incident from air on a water surface. What are the wavelength, frequency and speed of

   • (a) reflected, and
   • (b) refracted light? Refractive index of water is 1.33.
2. 2.
   What is the shape of the wavefront in each of the following cases:

   • (a) Light diverging from a point source.
   • (b) Light emerging out of a convex lens when a point source is placed at its focus.
   • (c) The portion of the wavefront of light from a distant star intercepted by the Earth.
3. 3.
   The refractive index of glass is 1.5. What is the speed of light in glass? (Speed of light in vacuum is 3.0 × 10^8 m s^-1) (b) Is the speed of light in glass independent of the colour of light? If not, which of the two colours red and violet travels slower in a glass prism?
4. 4.
   In a Young's double-slit experiment, the slits are separated by 0.28 mm and the screen is placed 1.4 m away. The distance between the central bright fringe and the fourth bright fringe is measured to be 1.2 cm. Determine the wavelength of light used in the experiment.
5. 5.
   In Young's double-slit experiment using monochromatic light of wavelength lambda, the intensity of light at a point on the screen where path difference is lambda, is K units. What is the intensity of light at a point where path difference is lambda/3?
6. 6.
   A beam of light consisting of two wavelengths, 650 nm and 520 nm, is used to obtain interference fringes in a Young's double-slit experiment.

   • (a) Find the distance of the third bright fringe on the screen from the central maximum for wavelength 650 nm.
   • (b) What is the least distance from the central maximum where the bright fringes due to both the wavelengths coincide?