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Convex lens having focal length f, and c...

Convex lens having focal length f, and concave lens having focal length f2 are placed in contact. Out of conditions given below, which condition supports this combination to behave like concave lens ?

A

`f_1=f_2`

B

`f_2 lt f_1`

C

`f_2 gt f_1`

D

`f_1f_2=1`

Text Solution

Verified by Experts

The correct Answer is:
A, B
`1/f=1/f_1-1/f_2`
For concave lens `f_2` is negative.
`therefore1/f=1/f_1-1/f_2`
If `f_2 lt f_1`,f will be negative and combination behaves as concave lens.
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