Calculate equalant focal length of plano convex lens for following case :–
(i) When curved surface is silvered.
(ii) When plane surface is silvered.

Explanation

(I ) P `= 2 P_(L ) + P_(M)`
`(1)/(F) = (2 )/(f_(e )) + (1)/(F_(m ))`
`rArr ( 1)/(F ) = (2(mu -1))/( R ) + (2 )/(R )`
`(1)/(F ) = (2mu)/( R ) rArr F = (R )/( 2mu)`

(ii) `P= 2P_(L) + P_(M)`
`(1)/( F ) = (2)/(f_(L)) + (1)/( f_(m))`
`rArr (1)/( F) = (2(mu-1))/(R ) + (1)/( prop)`
`F = (R )/(2(mu-1))`