With the help of a labelled diagram, explain how a concave lens diverges a beam of parallel light rays.

If two lenses (convex) are in contact with each other, what happens to the ray after refraction?

A convex lens forms a real and inverted image of a needle at a distance of 50 cm from it. Where is the needle placed in front of the convex lens if the image is equal to the size of the object? Also, find the power of the lens.

An object lies at a distance of 2f from a concave lens of focal length f. Draw a ray-diagram to illustrate the image formation.

The boy walks towards the mirror at a speed of 1m/ s. At what speed does his image approach him?

Describe with the help of a diagram, the nature, size and position of the image formed when an object is placed beyond the centre of curvature of a concave mirror.

1. How can you bend light away from the normal?
2. How must light travel out of a substance if it is not going to be refracted?

State and define the S.I. unit of power of a lens.

An object is placed just outside the principal focus of concave mirror. Draw a ray diagram to show how the image is formed, and describe its size, position and nature.

A pencil when dipped in water in a glass tumbler appears to be bent at the interface of air and water. Will the pencil appear to be bent to the same extent, if instead of water we use liquids like, kerosene or turpentine. Support your answer with reason.