Q. A step index fibre has a relative refractive index of 0.88%. What is the critical angle at the corecladding interface
A) $60{^\circ}$
B) $75{^\circ}$
C) $45{^\circ}$
D) None of these
Explanation
(d) Here $\frac{\mu_{1} - \mu_{2}}{\mu_{1}} = \frac{0.88}{100} \Rightarrow \frac{\mu_{2}}{\mu_{1}} = 0.9912$
$\therefore$ Critical angle $\theta_{c} = \sin^{- 1}{\left( \frac{\mu_{2}}{\mu_{1}} \right) = \sin^{- 1}{(0.9912)}} = 82{^\circ}24'$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.