Question

A Concave mirror has a magnification of - 2.5 cm if its focal length is 20cm find its image and object
position ?
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Answer 1

Explanation:

magnification=-v/u

5/2=-v/u

u=-2v/5

1/f=1/v+1/u

1/20=1/v-5/2v

1/20=2-5/2v

v=-30cm

u=-2×(-30)/5

u=12cm

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Answer 2

Answer:

v=-40 and u=-16

Explanation:

m=-2.5

-v/u=-2.5

v=5/2

from mirror formula

1/v+1/u=1/f

2/5u+1/u=-1/20

u=-28cm

v=-70cm