Question

As you bring a prism close to the angle of total internal reflection, what happens to the angle of the refracted beam outside the prism? What happens to its intensity? What happens to the intensity of the beam inside the prism?

Answer 1

as a prism is brought close to the angle of total internal reflection, also known as the critical angle, the angle of refracted beam goes on increasing and approaches 90⁰. The intensity of the refracted beam goes on decreasing, becoming zero as the prism reaches the critical angle. The intensity of the beam inside the prism, on the other hand, goes on increasing and becomes maximum at the critical angle. At any angle greater than critical angle there will be no refracted beam going out of the prism. The entire light will get reflected back into the prism.