Question

Find the power of lens which forms a real & inverted image of magnification – 1 at a distanceof 40 cm from its optical centre.

Answer 1

Explanation:

magnification=v/u

by using this we can get u=40 cm

by using lens formula

1/f=1/v-1/u

v=40 cm

u=-40cm

1/f=1/40+1/40=2/40=1/20

f=20cm

P=100/f=100/20 =+5D