Question

The combination of a convex lens of power $+2D$ and concave lens of power $-2D$, acts as a:

• A. glass slab
• B. convex lens
• C. concave lens
• D. data insufficient

Answer 1

The correct option is A glass slab

Convex lens is converging lens while concave lens is diverging lens. If these two types of lens of same power are combined together, the diverging power of one will be cancelled out by the converging power of the other. So the combination will act like a glass block.