Question

calculate focal length of a mirror. if the size of image is three times of the object size?​

Answer 1

Answer:

4/3v will be the focal length

Answer 2

1/f = 1/S + 1/S’

Where f is the focal length, S is the object distance and S’ is the image distance.

Magnification is given by S’/S = 3.

So S’ = 3S.

Plug that into first equation to get f.

1/f = 1/S + 1/3S.

1/f = (3S + S)/(3S^2)

f = 3S/4