Two convex lenses of power 2 D and 5 D are separated by a distance 1 3 m . The power of the optical system formed is

Question

Two convex lenses of power 2 D and 5 D are separated by a distance 1 3 m . The power of the optical system formed is, + 2 D, - 2 D, - 3 D, + 3 D

MARKS App · Accepted Answer

Given P 1 = 2 D P 2 = 3 D d = 1 3 m We know that 1 F = 1 f 1 + 1 f 2 - d f 1 . f 2 ∴ P = P 1 + P 2 - d P 1 . P 2 = 2 + 3 - 1 3 × 2 × 3 ⇒ P = 3 D