Question

What property of lens changes when it is dipped in water

Answer 1

The focal length of lens increases when it is dipped in water.

Answer 2

lens focal length depend upon refractive index of medium . so, if we change the medium , change the refractive index. hence, change it focal length .

e.g 1/f = (u -1)( 1/R1 - 1/R2)

here u is relative refractive index of medium . let initially its value u

after submerged in water which refractive index is d then,

1/f' = (u/d -1){ 1/R1 - 1/R2}

if d >u then,
u/d <1
( u/d -1)<0
hence, focal length will be negative if initial focal length positive .



here you can see that focal length will be change when we dipped lens in water .