The following table gives the refractive indices of a few media,

	1	2	3	4	5
Medium:	Water	Crown glass	Rock salt	Ruby	Diamond
Refractive index:	1.33	1.52	1.54	1.71	2.42

Use this table to give an example of:

1. A medium pair so that light speeds up when it goes from one of these medium to another.
2. A medium pair so that light slows down when it goes from one of these medium to another.

What do you mean by laterally inverted?

A ray of light is incident on a convex mirror as shown. Redraw the diagram and complete the path of this ray after reflection from the mirror. Mark angle of incidence and angle of reflection on it.

Your eye contains a convex lens. Why is it unwise to look at the sun?

An object is placed at a distance of 15 cm from a concave lens of focal length 30 cm. List four characteristics (nature, position, etc.) of the image formed by the lens.

When a light ray passes from air into glass, what happens to its speed? Draw a diagram to show which way the ray of light bends.

A communications satellite in orbit sends a parallel beam of signals down to earth. If these signals obey the same laws of reflection as light and are to be focussed onto a small receiving aerial, what should be the best shape of the metal 'dish' used to collect them?

With the help of a labelled ray diagram, describe how a converging mirror can be used to give an enlarged upright image of an object.

A wall reflects light and a mirror also reflects light. What difference is there in the way they reflect light?

Draw ray diagrams showing the image formation by a concave mirror when an object is placed:
Between pole and focus of the mirror.