The focal length of a plano convex lens is 
and its refractive index is 1.5. It is kept over a plane glass plate with its curved surface touching the glass plate is filled by a liquid. As a result, the effective focal length of the combination becomes 
. Then the refractive index of the liquid is
a)
1.5
b)
2
c)
1.25
d)
1.33
The focal length of a plano convex lens is and its refractive index is 1.5. It is kept over a plane glass plate with its curved surface touching the glass plate is filled by a liquid. As a result, the effective focal length of the combination becomes . Then the refractive index of the liquid is
a)
1.5
b)
2
c)
1.25
d)
1.33
Question ID - 152964 | SaraNextGen Top Answer
The focal length of a plano convex lens is and its refractive index is 1.5. It is kept over a plane glass plate with its curved surface touching the glass plate is filled by a liquid. As a result, the effective focal length of the combination becomes . Then the refractive index of the liquid is
a)
1.5
b)
2
c)
1.25
d)
1.33
|
The focal length of a plano convex lens is |
|||||||
|
a) |
1.5 |
b) |
2 |
c) |
1.25 |
d) |
1.33 |
(c)
According to lens maker’s formula
The focal length of plano convex lens is
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or 
…(i)
The focal length of liquid lens is
[Using (i)]
Effective focal length of the combination is
