HC Verma Chapter 18 Problem 15 – Virtual image by convex lens

Given

Object u=-10 cm, f=15 cm (u less than f)

Find

Image distance v

Formula

1/v = 1/f + 1/u = 1/15 + 1/(-10) = -1/30

Solution

v = -30 cm (virtual, erect, magnified)

Answer

Object inside focal length: convex lens acts as magnifier

Diagram / Concept

m = (-30)/(-10) = +3

Notes

Convex lens as magnifying glass when object within focal length