EXERCISES

Monochromatic light of wavelength $589 \mathrm{nm}$ is incident from air on a water surface. What are the wavelength, frequency and speed of refracted light? Refractive index of water is $1.33$.

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?

A beam of light consisting of two wavelengths, $650 \mathrm{nm}$ and $520 \mathrm{nm}$, is used to obtain interference fringes in a Young’s double-slit experiment. Find the distance of the third bright fringe on the screen from the central maximum for wavelength $650 \mathrm{nm}$.

A beam of light consisting of two wavelengths, $650 \mathrm{nm}$ and $520 \mathrm{nm}$, is used to obtain interference fringes in a Young’s double-slit experiment. What is the least distance from the central maximum where the bright fringes due to both the wavelengths coincide?

In a double-slit experiment the angular width of a fringe is found to be $0.2°$ on a screen placed $1 \mathrm{m}$ away. The wavelength of light used is $600 \mathrm{nm}$. What will be the angular width of the fringe if the entire experimental apparatus is immersed in water? Take refractive index of water to be $\frac{4}{3}$.

What is the Brewster angle for air to glass transition? (Refractive index $=1.5$)

Light of wavelength $5000\mathrm{ }\stackrel{0}{\mathrm{A}}$ falls on a plane reflecting surface. What are the wavelength and frequency of the reflected light? For what angle of incidence is the reflected ray normal to the incident ray? Take, $c=3\times {10}^8 \mathrm{m}/\mathrm{s}$

Estimate the distance for which ray optics is good approximation for an aperture of $4 \mathrm{m}\mathrm{m}$ and wavelength $400 \mathrm{n}\mathrm{m}$.