Question

how far an object should be placed from the concave mirror of the focal length 9m in order to get a sharp image on the screen 12m away from the mirror?​

Answer 1

Answer:

Focal length = - 9m

Image distance = -12m

Object distance = u

1/v+1/u=1/f

1/-12 +1/u = 1/ -9

1/u = 1/-9 -(1/-12)

1/u = 1/ -9+1/12

1/u = -4+3/36

u = - 36 m

The object should be placed 36m in front of the mirror.

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