A ray of light is incident at the interface between medium A and medium B as shown

in Figure 1a. The refractive index of medium A and medium B is 1.42 and 1.31

respectively. The light ray is totally internally reflected back into medium A. After that,

medium B is replaced with a layer of water that has a refractive index of 1.33 as shown

in Figure 1b.

Determine if total internal reflection will also occur at the Medium A-water interface in

Figure 1b. Assume that the incident angle in Figure 1a is the same as the incident

angle in Figure 1b. Show your workings clearly and explain your reasoning.