In a plane mirror,the distance between the image and the mirror is the same as the distance between the object and the mirror.

What is a prism?

The figure shows a ray of light as it travels from medium $A$ to medium $B$. The refractive index of medium $B$ relative to medium $A$ is:

What is the angle of incidence for a light ray incident on a glass slab such that it does not undergo refraction (in $^{\circ}$)?

For the same angle of incidence in media $P, Q$ and $R$,the angles of refraction are $45^{\circ}, 35^{\circ}$ and $15^{\circ}$ respectively. In which medium will the velocity of light be minimum? Give reason.

What is the focal length of the objective of an astronomical telescope as compared to that of the eyepiece?