Question

A concave lens has focal length of 25 cm. At what distance from the lens, a 7.5 cm tall object

be placed so that it forms an image at 10 cm from the lens? Also calculate the size of the image

formed.​

Answer 1

Explanation:

f.l.=25cm

height of object =7.5 cm

v=10 cm

using lens formula

1/v-1/u=1/f

1/10-1/u=1/25

-1/u=2-5/50

-1/u=-3/50

u=50/3

for calculating size of object use formula of magnification