Question

An object of height 2cm is held at a distance of 40 cm in front of a concave lens of power_5D find the size of the image?

Answer 1

Concave lens

ho = 2 cm

u = -40 cm

P = 1/f

5=1/f

f= 1/5 x 100cm

f=20 cm

Using lens formula

1/v - 1/u = 1/f

1/v = 1/20 + 1/-40

1/v = 2-1/40

1/v = 1/40

v=40cm

hi/ho = v/u

hi=v/u x ho

hi = 40/-40 x 2

hi = 2 cm

Image height is 2cm