Question

What is total internal reflection?

Hint:

Remember the two key conditions for TIR: 1. Denser to Rarer medium, and 2. Angle of incidence \(>\) Critical angle (\(i > i_c\)). Applications like optical fibers, mirages, and the sparkling of diamonds are all based on this principle.

Answer 1

Step 1: Understanding the Concept:
Total Internal Reflection (TIR) is a special case of reflection that occurs under specific conditions at the boundary between two transparent media. It's the principle behind optical fibers.

Step 2: Detailed Explanation:
For TIR to occur, two necessary conditions must be met: \begin{enumerate} \item Medium of Travel: The light ray must be traveling from a medium with a higher refractive index (optically denser) to a medium with a lower refractive index (optically rarer). For example, from water to air, or from glass to water.
\item Angle of Incidence: The angle of incidence (\(i\)) in the denser medium must be greater than a specific angle called the critical angle (\(i_c\)). The critical angle is the specific angle of incidence for which the angle of refraction is 90 degrees.
\end{enumerate} When these two conditions are satisfied, no light is refracted into the rarer medium; instead, the entire ray is reflected back into the denser medium, following the laws of reflection (angle of incidence = angle of reflection).

Step 3: Final Answer:
Total internal reflection is an optical phenomenon in which a light ray traveling from an optically denser medium to an optically rarer medium is completely reflected back into the denser medium. This happens when the angle of incidence at the interface is greater than the critical angle for the pair of media.