Question

An object is kept at a distance of 20 cm in front of a
mirror, its image is formed on same side of the
mirror (real image) at distance of 30 cm. Find the
nature and focal length of the mirror
[Ans. - 12 cm​

Answer 1

Object distance = u = -20 cm

Image distance = v = -30 cm

By Mirror Formula,

1/v + 1/u = 1/f

-1/20 - 1/30 = 1/f

-5/60 = 1/f

f = -12 cm

Nature :- Real, inverted, Smaller than object.

Answer 2

Answer:

nature is concave mirror

Explanation:

u= -20

v= -30

1/f=1/v+1/u

1/f= 1/-20+1/-30

1/f=-5/60

f= -60/5

f= -12