Asked by Abhijeetoo7 | 12th Feb, 2010, 02:28: AM

Expert Answer:

Dear student,

Let n1 = refractive index of surrounding medium
n2 = refractive index of lens
1/f is proportional to n2/n1 - 1
  water has higher refractive index than air. Therefore when the lens is put in water, then n1 increases.
Therefore n2/n1 decreases.
Or n2/n1 - 1 decreases.
Therefore 1/f decreases.
Therefore f increases.
Focal lengthwill increase.

We hope this helps.


Answered by  | 12th Feb, 2010, 10:12: AM

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