Question

An object is placed 25 cm from a convex lens, whose focal lenght is 16cm. The image distance is__________.

Answer 1

1/-25 + 1/v = 1/16
1/v = 1/16 + 1/25
1/v = 25+16/400
1/v = 41/400
v = 400/41 cm = 9.75 cm

image distance is 9.75 cm

Answer 2

Given,
       1/u=25  ,   1/f=16
Lens formula=>1/f=1/v-1/u
                       1/v=1/f+1/u
                            =1/16+1/25
                            =25+16/400
                             =41/400
                           v=400/41
                           v=9.75cm