4 Two triangular glass prisms are placed together as shown. Outside the prisms is air.
a. A ray of light perpendicularly strikes the face of one of the prisms. Calculate the angle, ̄̈ጨ, at which the light ray exits the second prism.
b. Determine the angle of incidence, ̄̈ጨ, that would result in the ray being refracted along the interface between the two prisms.