Question

A convex lens produces three timea magnified real image of object place at a distance of 10cm from it . find the position of image and the focal length of lens. What will be the power of the lens

Answer 1

u= -18 cm

m= -3

m= v/u

-3= v/-18

v=-3 * -18

v= 54 cm

1/v - 1/u = 1/f

1/54+ 1/18= 1/f

(1+3)/54 = 1/f

4/54=1/f

f = 13.5 cm

P=1/f(in cm)

P=100/13.5

P=7.4 D