Question

Two lenses of power +3.5D and -2.5D are placed in contact. Find the power and focal lenght of the lens in combination.

Answer 1

Hello,

Given that

P₁ = 3.5 D

P₂ = -2.5 D

Power of lens in combination

P = P₁ + P₂

= 3.5 -2.5 = 1D

Focal length of lens in combination

f = 1/P = 1/1 = 1m