Name: Constructive and Destructive Interference of Light Waves
Uploaded: 2019-07-19
Duration: 11 min 15 s
Description: If 2 balls rolling on a surface with a certain speed approach each other, then we expect that they will collide, and their velocities get altered after the c...

Question

What is total internal reflection. Explain the phenomenon using Huygen's principle.

Accepted Answer

When light travels from an optically denser medium to a rarer medium, it bends away from the normal in the rarer medium. It is partly reflected back into the same medium also. This reflection is called internal reflection. When the angle of incidence is increased, the angle of refraction also increases. At a certain angle of incidence, the angle of refraction is $90^{0}$ . The refracted ray grazes the interface. If the angle of incidence is further increased, refraction is not possible and the incident ray is totally reflected. It is called total internal reflection.

According to Huygen's principle, light travels in the form of a wavefront. Let the light travels from a denser medium to a rarer medium. Consider a plane wavefront AB incident obliquely on the interface separating the two media. Then CD will be the refracted wavefront.

When the angle of incidence is equal to the critical angle, then the wavefront can not be refracted in the rarer medium. It will just graze the surface. In this case, the angle of refraction is $90^{0}$ .

The incident angle is further increased and is more than the critical angle the wavefront is reflected in the same medium as shown in the figure. CD is a totally internally reflected wavefront.

Telangana Board Solutions for Chapter: Wave Optics, Exercise 1: MODEL QUESTIONS (IPE PATTERN)

Telangana Board Physics Solutions for Exercise - Telangana Board Solutions for Chapter: Wave Optics, Exercise 1: MODEL QUESTIONS (IPE PATTERN)

Questions from Telangana Board Solutions for Chapter: Wave Optics, Exercise 1: MODEL QUESTIONS (IPE PATTERN) with Hints & Solutions

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