Question

A wiere mesth consisting of very small squares is viewed at a distances of `8cm` through a magnifying lens of fcoal length `10cm`, kept close to the eye. The magnification produced by the lens is
A. 5
B. 8
C. 10
D. 20

Answer 1

(a) `1/f=1/v-1/u`………(i)
Given `f=10cm` (as lens is converging)
`u=-8cm` (as object is placed on left side on the lens)
Substituting these values in Eq. (i) We get
`1/10=1/v-1/(-8)implies1/v=1/10-1/8implies1/v=(8-10)/80`
`:. V=80/(-2)=-40cm`
Hence, magnification produced by the lens
`m=v/u=(-40)/(-8)=5`