#### Question

The power of a concave lens is 10 D and that of a convex lens is 6 D. When these two lenses are placed in contact with each other, the power of their combination will be :

(a) +16 D

(b) +4 D

(c) −16 D

(d) −4 D

#### Solution

-4 D

The powers of the lenses add up when brought in contact.

So, net power = +6 D + (-10 D) = -4 D.

Is there an error in this question or solution?

Solution The Power of a Concave Lens is 10 D and that of a Convex Lens is 6 D. When These Two Lenses Are Placed in Contact with Each Other, the Power of Their Combination Will Be : (A) +16 D (B) +4 D (C) −16 D (D) −4 D Concept: Refraction of Light - Image Formation by Lenses - Concave Lens.