Question

A 10D lens is used as a magnifier. Where should the Object be placed to obtain maximum angular magnification for a normal eye.

Answer 1

Given:

P=10D

Maximum angular magnification is achieved when the final  

image is formed at near point

V= -25cm

P=100/f

f=100/10=10cm

By lens formula:

1/f=1/v-1/u

-1/25-1/u=1/10

-1/25-1/10=1/u

1/u=-2-5/50

u=-50/7= - 7.1 cm

∴ At a distance of 7.1cm the Object should be placed to obtain maximum angular magnification for a normal eye