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Prateek Asked :

25-09-2021 Electromagnetic Theory

Q. Numerical aperture is expressed as the

A. NA = sin θa
B. NA = cos θa
C. NA = tan θa
D. NA = sec θa

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Dapzoi Verified
Commented on 2021-09-25 11:05:12 (IST)
Answer: A

Explanation: The numerical aperture is the measure of how much light the fiber can collect. It is the sine of the acceptance angle, the angle at which the light must be transmitted in order to get maximum reflection. Thus it is given by NA = sin θa.