Answer to Question #173634 in Physics for ANJU JAYACHANDRAN

Question

7b) In an optical fibre the refractive index of core is 1.52 and that of cladding is 1.48. 

Calculate the critical angle and acceptance angle when the fibre is immersed in 

glycerin. Refractive index of glycerin is 1.47.

Answer 1

Find the acceptance angle:

$$\theta_a=\text{arcsin}\frac{n_2}{n_1}=\arcsin\frac{1.48}{1.52}=76.8°.$$

Find the critical angle:

$$\theta_c=90°-\theta_a=13.2º.$$