Question

An illuminated object lies at a distance of 1 m from the screen. A convex lens is used to form the image of object on a screen placed at a distance of 75cm from the lens. Find the focal length and the magnification

Answer 1

V= 75cm
U= -100cm

Therefore According to lens rule:- 1/f=1/v-1/u

so

1/f= 1/75-(1/-100)

therefore f =300 cm

for magnification

m= v/u

= 75/-100
= -0.75 dioptre