Question

# In optical fiber, refractive index of inner part is 1.68 and refractive index of outer part is 1.44. The numerical aperture of the fibre is

A
0.5653
B
0.6653
C
0.7653
D
0.8653
Solution
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#### Numericalapertureoffibre=√μ21−μ22=√1.682−1.442=√2.8224−2.0736 =√0.7488=0.8653

1
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