Question

A convex lens of a focal length 30cm produces a real image 3 times magnified.Find the object distance

Answer 1

HEY YOUR ANSWER ...

Given:f = 20 cm
m = -3 = v/u
v = -3u
Lens formula: 1/v - 1/u = 1/f
                         1/(-3u) - 1/u = 1/20
        - 4/(3u) = 1/20
            3u = - 4 x 20
               u = -80/3 = - 26.6 cm
The object is at a distance of 26.6 cm to the left from the optic centre of the lens.

HOPE IT HELPS YOU !!!

Answer 2

Answer:Hii

Here is your answer

Given,

f =20 cm

m = -3 = v/u

We know that

1/v -1/u = 1/f

=> 1/-3u -1/u = 1/20

=> -1 -3u/3u = 1/20

=> -4/3u = 1/20

=> -4×20 = 3u

=> 3u = -80

=> u = -80/3

= -26.6 cm

Therefore the object is at a distance of -26.6 cm

Explanation: Hope it helps you.....