TeXes Science Practice Test

What happens during total internal reflection?

1. Light passes into a different medium

2. Light is absorbed by the medium

3. Light stays in the original medium

4. Light is refracted

The correct answer is: Light stays in the original medium

During total internal reflection, light is completely reflected at the boundary of two different media when it travels from a denser medium to a less dense one, such as from water to air. This phenomenon occurs when the angle of incidence exceeds the critical angle specific to those two materials. Because the light cannot pass into the less dense medium, it remains entirely within the original medium, contributing to the effect. This process is essential in applications such as optical fibers, where light signals must be efficiently transmitted over long distances without losing intensity. Since the light does not enter the second medium nor absorb into the original one, it effectively remains in the original medium, which allows for the preservation of light energy and optimal transmission.