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Two point objects are placed on principa...

Two point objects are placed on principal axis of a thin converging lens. One is 20cm from the lens and other is on the other side of lens at a distance of 40 cm from the lens. The images of both objects coincide. The magnitude of focal length of lens is :-

A

`80/3`cm

B

`40/3`cm

C

`40` cm

D

`20/3` cm

Text Solution

Verified by Experts

The correct Answer is:
A
For object `O_(1)`
`1/v+1/20=1/v`……….1
for object `O_(2)`
`1/v+1/40=-1/f`………….2
from equation 1 and 2 we get
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