Question

an object is placed at a distance of 30 cm from a convex mirror the magnification produced is 1 upon 2 where should the object be placed to get a magnification of 1 upon 3​

Answer 1

Answer:

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Explanation:

In first case when magnification is 1/2

-v/u=1/2

u=-2v

From mirror formula

1/30+1/15=1/f

f=10cm

Thus focal length =10cm

In second case.

-v/u=1/3

u=-3v

From mirrors formula

-1/3v+1/v=1/20

2/3v=1/10

v=20/3cm

Since, u=-3v

Therefore,u=-3*20/3

u=-20cm

Justification:-

m= -v/u

1/3=-20/3*-1/20

1/3=1/3

Therefore, the object should be placed at a distance of 20cm.