question_answer

A ray of light is incident on the surface of a glass slab at \[\text{6}{{\text{0}}^{\text{o}}}\text{.}\] The refractive index of glass, if the reflected and refracted rays are mutually perpendicular to each other, will be:

A)  1.5             

B)  4.16

C)  2.25           

D)  1.73

Correct Answer: D

Solution :

 From Snells law \[\mu =\frac{\sin i}{\sin r}\] Given, \[i+r={{90}^{o}}\Rightarrow r={{90}^{o}}-i\] \[\therefore \] \[\mu =\frac{\sin i}{\sin ({{90}^{o}}-i)}=\tan i\] Given, \[i={{60}^{o}},\]therefore \[\mu =\tan {{60}^{o}}=\sqrt{3}=1.73\]