Question

An equiconvex lens of power P is cut perpendicular to its principal axis, into 2 equal parts, power of each part?

• A. \( P/2 \)
• B. \( 2P \)
• C. \( P \)
• D. Zero

Hint:

When cutting a lens along the principal axis, the focal length doubles and the power of each part is halved.

Answer 1

The Correct Option is A

When a lens is cut into two equal parts along the principal axis, the focal length of each part is doubled because the curvature of each lens surface is reduced by half. The power \( P \) of a lens is given by: \[ P = \frac{1}{f} \] Where \( f \) is the focal length of the lens. If the lens is cut in half, the focal length of each part becomes \( 2f \), and the power becomes: \[ P_{\text{new}} = \frac{1}{2f} = \frac{P}{2} \] Thus, the power of each part of the lens is \( P/2 \).