## Question

A ray of light travelling in glass (refractive index, * _{a}n_{g}* = 3/2) is incident on a horizontal glass-air surface at the critical angle

*c*. If a thin layer of water (refractive index,

*= 4/3) is now poured on the glass-air surface, at what angle will the ray of light emerge into air at the water-air surface?*

_{a}n_{w}### Solution

90^{o}

The refractive index of water with respect to glass is

The ray of light will emerge at the water-air surface into air parallel to the surface.

#### SIMILAR QUESTIONS

A man 1.8 m tall wishes to see full-length image in a plane mirror. The length of the shortest mirror in which he can see his entire image is

An illuminated object is placed between two plane mirrors mutually perpendicular to each other how many images are formed?

A 2.0 cm tall object is placed 15 cm from a concave mirror of focal length 10 cm. How far is the image from the mirror?

An object 1.0 cm tall is placed 8 cm in front of a concave mirror of radius of curvature 24 cm. What is the size and the nature of the image?

A concave mirror forms a real image four times the size of the object placed at a distance of 10 cm from it. What is the radius of curvature of the mirror?

In Young’s double slit experiment, the 10^{th} maximum of wavelength λ_{1} is at a distance *y*_{1} from its central maximum and the 5^{th} maximum of wavelength λ_{2} is at a distance *y*_{2} from its central maximum. The ratio *y*_{1}/*y*_{2}will be

White light is used to illuminate the two slits in Young’s double slit experiment. The separation between the slits is *d* and the distance between the screen and the slit is *D* (>> *d*). At a point on the screen directly in front of on the slits, certain wavelengths are missing. The missing wavelengths are (here *m* = 0, 1, 2, … is an integer)

In Young’s double slit experiment using two identical slits, the intensity of the maximum at the centre of the screen is *I*. What will be the intensity at the centre of the screen if one of the slits is closed?

Glycerine (refractive index 1.4) is poured into a large jar of radius 0.2 m to a depth of 0.1 m. There is a small light source at the centre of the bottom of the jar. Find the area of the surface of glycerine through which the light passes.

The radius of curvature of the convex surface of a thin plano-convex lens is 20 cm. Refractive index of the medium of the lens is 1.5. Calculate the focal length of the lens.