Total Internal Reflection Study Guide


A mirror of good quality material reflects more than 90 percent of the light that falls on it. And the rest, 10 percent, is absorbed by the mirror. The reflection of all rays of light would require the concept of refraction. For more, let’s start understanding the concept of total internal reflection. 


  • Total internal reflection definition is the phenomenon of a light ray traveling through a more optically dense medium to a less optically dense medium.
  • A medium can be defined as water or glass.
  • Light passes from the surrounding surface to back in the medium.
  • However, there is a  difference between internal reflection and total internal reflection. 
  • Reflection is the phenomenon that happens in almost every type of wave, such as sound, water, etc., while the total internal reflection occurs only with the light ray.



There are two main conditions for the occurrence of total internal reflection of light, they are:

  • The light ray must travel from a more dense medium to a less dense medium.
  • It must form the angle of incidence, which should be greater than the critical angle.




The application of total internal reflection is as follows:


A mirage occurs due to atmospheric refraction. Mainly, an optical illusion is responsible for its occurrence. A mirage occurs at a short distance; it can be on a road or desert and shows the appearance of water. 


Why do diamonds shine? Diamonds shine because the critical angle of a diamond is 23 degrees. Thus, when the light ray falls on the diamonds’ faces, the angle of incidence becomes more than the critical angle. 


Optical fibers help in telecommunication and are considered to be one of the fastest modes of media transfer. Why so? Because the optical fibers suffer total internal reflection. The angle of incidence becomes greater than the critical angle, making it valuable. Endoscopy also makes use of optical fibers. 


There are several total internal reflection examples. Some of them are:

  • Components of telescopes, microscopes, and binoculars
  • Vehicle rain sensors
  • Fingerprinting sensors
  • Cracked glassware


  • Total internal reflection happens when the light ray passes through the more dense optical medium to the less dense optical medium.
  • The angle of incidence must be greater than the total internal reflection critical angle.
  • There are several applications of total internal reflection including, but not limited to, mirages, diamonds, and optical fibers.


Q. What are total internal reflection examples?

Examples of total internal reflection are the shining diamonds, cracked glassware, mirage, optical fibers, etc.

Q. Why is it called total internal reflection?

Because it has the tendency to occur when it passes from a denser medium to a less dense medium.

Q. What is the application of total internal reflection?

The application of total internal reflection are telescopes, microscopes, binoculars, diamonds, fingerprinting sensors, periscopes, spectroscopes, etc.                 

Q. What is a total internal reflection in physics?

It is the phenomenon of the light ray traveling through the more optically denser medium to the less optically denser medium.                                                                                                          

We hope you enjoyed studying this lesson and learned something cool about Total Internal Reflection! Join our Discord community to get any questions you may have answered and to engage with other students just like you! We promise, it makes studying much more fun!😎


  1. Total Internal Reflection: Accessed 14th April 2022.
  2. Total Internal Reflection:  Accessed 14th April 2022.
  3. Total Internal Reflection:  Accessed 14th April 2022.

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