Question

The real image of an extended object placed in front of concave mirror is formed at the distance of 40cm from the object. if the image is 3 times bigger than the object , the magnitude of focal lenght of the mirror is.

Answer 1

Explanation:

given 3v=u

1/f=1/v+1/u

1/f=1/v+1/3v

f=3v/4

v=40cm

f=3×40/4

f=30cm