Ray Optics And Optical Instruments Ques 6

6. A ray of light travelling in a transparent medium of refractive index $\mu$, falls on a surface separating the medium from air at an angle of incidence of $45^{\circ}$. For which of the following value of $\mu$ the ray can undergo total internal reflection?

[2010]

(a) $\mu=1.33$

(b) $\mu=1.40$

(c) $\mu=1.50$

(d) $\mu=1.25$

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Answer:

Correct Answer: 6.(c)

Solution:

  1. (c) For total internal reflection,

$ \begin{aligned} & \mu \geq \frac{1}{\sin C} \geq \sqrt{2} \geq 1.414 \\ & \Rightarrow \mu=1.50 \end{aligned} $