Question

What do you mean by total internal reflection ? Show it by drawing ray diagram.

Hint:

Remember the key application of TIR is in optical fibers, where light signals are transmitted over long distances with minimal loss of intensity. Other examples include the sparkling of diamonds and mirages.

Answer 1

Step 1: Understanding the Concept: 
Total Internal Reflection (TIR) is the phenomenon where a wave, such as light, traveling from a denser medium to a less dense medium is completely reflected back into the denser medium. 
Step 2: Conditions for TIR: 
For total internal reflection to occur, two conditions must be met: 
The light ray must travel from a denser optical medium to a rarer optical medium. The angle of incidence in the denser medium must be greater than a specific angle called the critical angle (\(i_c\)). The critical angle is the angle of incidence for which the angle of refraction is 90\(^{\circ}\). 
Step 3: Ray Diagram: 

Diagram Explanation:
Ray 1: The angle of incidence \(i_1\) is less than the critical angle \(i_c\). The ray refracts into the rarer medium, bending away from the normal.
Ray 2: The angle of incidence \(i_2\) is equal to the critical angle \(i_c\). The refracted ray travels along the boundary of the two media (angle of refraction \(r_2 = 90^\circ\)).
Ray 3: The angle of incidence \(i_3\) is greater than the critical angle \(i_c\). The ray does not refract but is completely reflected back into the denser medium, following the laws of reflection (\(i_3 = r_3\)). This is Total Internal Reflection.