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?

Explanation:

Total Internal Reflection (TIR) occurs when the angle of incident exceeds the value of critical angle and as a result of which the light gets internally reflected and does not refract the light enters at one point and exits at the other like that of an optical fiber.

Critical angle is defined as that incident angle for which the refracted angle is a right angle.

Now, in case a prism is brought close to the angle of TIR, the refracted beam angle increases up to the point where it reaches .

As it exceeds , the beam will be internally reflected without any refraction. So, in reaching the point of TIR, the intensity of the refracted beam decreases and is completely diminished to 0 at critical angle.

The beam intensity inside the prism increases and is maximum at the point of TIR, i.e., at critical angle.

Once TIR is initiated, i.e., the angle exceeds the critical angle, internal reflection occurs with no refracted rays.