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Question
A glass material A with an optical fibre is made has a refractive index of 1.55. This material is clad with another material whose refractive index is 1.51. The light in the fibre is launched from air. Calculate the numerical aperture of the fibre.
Solution
Given: n1=1.55
n2=1.51
To Find: NA=?
Formula: `NA=sqrt(n_1^2-n_2^2)`
`NA=sqrt(1.55^2-1.51^2)`
NA=0.35.
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