Question Detail
Question
A lens of 15 cm focal length forms an image four times the size of an object. The distance of the image from the lens is
Correct Answer
Option D is the correct answer.
Detailed Explanation
m = v/u = 4 => v = 4u. 1/f = 1/u + 1/v = 1/u + 1/(4u) = 5/(4u) => u = 5f/4 = 5 × 15 / 4 = 18.75 cm. v = 4 × 18.75 = 75 cm.
Hint
Use m = v/u and the lens formula.