There are four light rays incident on a right angled prism in a direction as shown in the figure. The refractive index of prism material for the rays are 1.43, 1.39, 1.38, 1.21 respectively. The ray that suffers total internal reflection is

I

Here angle of incidence,$ i = 45^o$

So for Total Internal Reflection $i \ge i_c$

sin i_c = \(\frac{1}{µ}\)

If i_c = 45° then, μ = 1.414

∴ Light with refractive index more than 1.41 will suffer total internal reflection while less than 1.41 will refract through opposite face.

Thus, only I (μ = 1.43) will suffer Total Internal Reflection.