Question

What is the position of the object placed on the side of reflecting surface of a concave mirror of focal length 20 cm if the image is formed at the distance of 40 cm from the mirror?

Answer 1

Answer:

-40cm

Explanation:

Focal length f=-20cm

Image distance =-40cm

Object distance =?

1/f=1/u+1/v

1/-20=1/u+1/-40

1/-20+1/40=1/u

-1/40=1/u

u=-40

40cm behind the mirror