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A double convex lens has power P and sam...

A double convex lens has power P and same radii of curvature R of both the surfaces. The radius of carvature of a surface of plano-convex lens made of the same meterial with power 1.5 P is :

A

2 R

B

`(R )/(2)`

C

`( 3 R)/(2)`

D

`(R )/(3)`

Text Solution

Verified by Experts

The correct Answer is:
D
`(1)/(P) = (n -1) ((1)/(R) - (1)/(-R))`
`(1)/(P) = (n -1) (2)/(R)` . . . (i)
`(1)/( 1.5 P) = (n -1) ((1)/(R) -(1)/(oo))` . . . (ii)
`(2)/( 3P) = (n -1) /(R)`
From eq. (i) and (ii)
`(3)/(2) = (R.)/(2R) rArr R. =(R)/(3)`
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