Question

A ray of light travelling in a transparent medium falls on a surface separating the medium from air at an angle of incidence ${45}^o$ and undergoes total internal reflection. lf $\mu$ is the refractive index of medium the possible values of $\mu$ are

• A. $\mu =1.3$
• B. $\mu =1.4$
• C. $\mu =1.5$
• D. $\mu =1.6$

Answer 1

Answer: (C), (D)

$\mu =1.5$
$\mu =1.6$

Since, the ray undergoes total internal reflection,
$\mu >\frac{1}{sinc}$

Now,$i=45$

Thus, $sinc<sini$

Thus, $\mu >\frac{1}{sini}$

OR, $\mu >\sqrt{2}$