Question

An object 50 cm tall is placed on the principal axis of convex lens. It's 20 CM tall image is formed on the screen placed at a distance of 10cm from the lens calculate the focal length of the lens.

Answer 1

Explanation:

v=20

u=-10

f=

1/v-1/u=1/f

1/20-1/-10=1/f

1/20+1/10=

10+20/200=

30/200=

1/6.7=1/f

6.7=f