A thin lens made of glass of refractive index 
has a focal length equals is 12 cm in air. It is now immersed in water 
Its new focal length is
a)
48 cm
b)
36 cm
c)
24 cm
d)
12 cm
A thin lens made of glass of refractive index has a focal length equals is 12 cm in air. It is now immersed in water Its new focal length is
a)
48 cm
b)
36 cm
c)
24 cm
d)
12 cm
Question ID - 152810 | SaraNextGen Top Answer
A thin lens made of glass of refractive index has a focal length equals is 12 cm in air. It is now immersed in water Its new focal length is
a)
48 cm
b)
36 cm
c)
24 cm
d)
12 cm
|
A thin lens made of glass of refractive index |
|||||||
|
a) |
48 cm |
b) |
36 cm |
c) |
24 cm |
d) |
12 cm |
1 Answer
127 votes
Answer Key / Explanation : (a) -
|
(a) Focal length in air is given by
The focal length of lens immersed in water is given by
When, Also, Given,
|
are radii of curvatures of the two surfaces of lens and 
is refractive index of glass with respect to liquid.
127 votes
Answer Link
127