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An object is placed 50cm from a screen a...

An object is placed 50cm from a screen as shown in figure.
A converging lens is moved such that line MN is its principal axis. Sharp images are formed on the screen in two positions of lens separated by 30cm. Find the focal length of the lens in cm.

Text Solution

Verified by Experts

The correct Answer is:
8
`f=(D^(2)-d^(2))/(4D)=(50^(2)-30^(2))/(4xx50)=8cm`
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