a concave mirror and a converging lens have the same focal length in the air. which one of the two will have greater focal length when immersed in water? explain why?

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Solution

Dear Student,

$f o c a l l e n t h o f l e n s i n w a t e r i s g i v e n b y \frac{1}{f} = ({}_{w}μ_{g} - 1) (\frac{1}{R_{1}} - \frac{1}{R_{2}}) B e c a u s e R I o f w a t e r i s l e s s t h a n R I o f g l a s s h e n c e f o c a l l e n g t h o f l e n s i n c r e a s e s i n w a t e r a s c o m p a r e t o i t s f o c a l l e n t h i n a i r . B e c a u s e f o c a l l e n g t h o f m i r r o r d o e s n o t d e p e n d s o n t h e R I o f t h e m e d i u m h e n c e f o c a l l e n g h t o f m i r r o r r e m a i n s s a m e i n t h e w a t e r . H e n c e l e n s h a s m o r e f o c a l l e n g t h i n w a t e r .$

Regards.

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