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The focal length of an equiconvex lens i...

The focal length of an equiconvex lens in air i equal to either of its radii of curvature. The refractive index of the material of the lens is …........

A

`4/3`

B

1.5

C

2.5

D

0.8

Text Solution

Verified by Experts

The correct Answer is:
A, B
Taking `R_1=R,R_2=-R,f=R`
Forconvex lens,
`1/f=(mu-1)(1/R_1-1/R_2)`
`1/R=(mu-1)(2/R)`
`therefore 1=2mu-2`
`therefore2mu=3`
`thereforemu=3/2=1.5`
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