Question

Focal length of a concave mirror is 20 cm what is nature of an image if an object is placed at 60 cm

Answer 1

Answer:

Hence image is formed on left side [due to negative sign] 60 cm away from mirror

Explanation:

Focal length f=−20 cm

Object distance u=−50 cm

Using

v

1

−

u

1

=

f

1

Or

v

1

−

(−50)

1

=

−20

1

We get v=−14.3 cm

Since, v is negative. So image formed is virtual.

Hence, virtual image is formed at a distance of 14.3 cm in front of the lens

Answer 2

Mirror Formula

→ 1/f = 1/v + 1/u

f = Focal Length

v = Image distance

u = Object distance

→ 1/(- 20) = 1/v + 1/(- 30)

→ - 1/20 + 1/30 = 1/v

→ (- 3 + 2)/60 = 1/v

→ - 1/60 = 1/v

→ v = - 60 cm

Hence image is formed on left side [due to negative sign] 60 cm away from mirror.

v = - 60 cm

BRAINLYPRINCE007