Total Internal Reflection: Practice Problem & Solution
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 Pre)
Solution Explained:
To solve this problem, we apply the core principles of Total Internal Reflection. Understanding the underlying formula is key to arriving at the correct answer below:
For total internal reflection, the incidence angle must be greater than the critical angle, so $\sin i > \sin \theta_c = \frac{1}{\mu}$. Given $i = 45^\circ$, we have $\frac{1}{\sqrt{2}} > \frac{1}{\mu} \implies \mu > \sqrt{2} \approx 1.414$. Among the options, only $\mu = 1.50$ satisfies this.
Leave a Reply