Question

An object is placed in front of a concave mirror and it’s image is formed at a distance of 30.0cm find the focal length of mirror

Answer 1

u= -30 cm

f= -20 cm

By using mirror formula,

1/v + 1/u = 1/f

1/v + 1/-30 = 1/-20

v= -60 cm

negative sign indicates that image is in front of the mirror

Therefore,

The distance between image and object = 60–30 = 30cm

Answer 2

Answer:

ans = 15cm

Explanation:

1/f = 1/u +1/v

u= 30 , v = -30

1/f = 1/15

f = 15cm