Power of a lens of focal length 25 cm is

[amp_mcq option1=”+2-5 Dioptre” option2=”+3 Dioptre” option3=”+4 Dioptre” option4=”+5 Dioptre” correct=”option3″]

This question was previously asked in

UPSC NDA-2 – 2021

The correct answer is C) +4 Dioptre.

The power of a lens (P) is defined as the reciprocal of its focal length (f), when the focal length is expressed in meters. The formula is P = 1/f.

Given focal length f = 25 cm. Convert this to meters: 25 cm = 0.25 m.
Power P = 1 / 0.25 m = 1 / (1/4) m = 4 Dioptre (D).
A positive power indicates a converging (convex) lens.

More similar MCQ questions for Exam preparation:-