Question

A concave lens of power -2D is placed in contact with a convex lens of power +1.5D what will be the resultant power

Answer 1

Answer: -0.5 D

Explanation:

The resultant power can be defined as the sum of powers of all the lenses placed in contact together.

P =P₁ + P₂ + P₃ +....

It is given that power of the concave lens is, P₁ = -2 D

Power of the convex lens is, P₂ = +1.5 D

Thus, the resultant power when these two lenses are placed in contact with each other are: P = P₁ + P₂ = -2 D + 1.5 D = -0.5 D.