A plano-concave lens has :

1. one surface convex and the other surface plane.
2. one surface concave and the other surface convex
3. one surface plane and the other surface concave
4. none of the above

The incorrect statement is :

1. both convexo-concave and concavo-convex lenses have one surface concave and the other surface convex.
2. a convexo-concave lens is thicker in the middle and has a converging action.
3. A concavo-convex lens is thicker in the middle and has a converging action.
4. a convexo-concave lens is thinner in the middle and has a diverging action.

A convex lens in its upper part has a prism with its base …………… and a concave lens in its upper part has a prism with its base …………… :

1. downward, upward
2. upward, downward
3. upward, upward
4. downward, downward

The correct differences between a convex and concave lens are :

(a) convex lens is thin in the middle and concave lens is thick in the middle.

(b) convex lens converges the incident rays towards the principal axis whereas concave lens diverges

(c) convex lens has a virtual focus and concave lens has a real focus.

1. (a)
2. (c)
3. (a), (b) and (c)
4. (b)