What is the relation between focal length and radius of curvature of a lens?Do the two focal lenghs of a lens  always have the same value?Are the focal lengths of a lens different for different medium?

Asked by joykphukan | 21st Jul, 2015, 09:13: PM

Expert Answer:

The relation between focal length and radius of curvature is given by lens maker's formula:
begin mathsize 12px style 1 over straight f equals open parentheses straight mu minus 1 close parentheses open square brackets 1 over straight R subscript 1 minus 1 over straight R subscript 2 close square brackets straight mu equals Refractive space index space of space material space of space lens space straight w. straight r. straight t. space space surrounding space medium straight R subscript 1 equals Radius space of space curvature space of space first space surface space of space lens straight R subscript 2 equals Radius space of space curvature space of space second space surface space of space lens end style
 
For a given perticular lens, its focal lenght always have the same vlaue.
 
From the given formula we can say that focal length of lens is different of different media.

Answered by Priyanka Kumbhar | 22nd Jul, 2015, 09:46: AM