question_answer

A ray of light is incident on the surface of a glass slab at \[{{60}^{o}}\]. 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 Snell's 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                 \[\mu =\tan {{60}^{o}}=\sqrt{3}=1.73\]