Name: Waves and Their Phases
Uploaded: 2019-07-19
Duration: 6 min 51 s
Description: In this video, we will learn how two or more waves can be studied in terms of their phases. Equations of two waves and graphs of two waves. Learn more!

Question

Prove laws of reflection using Huygens' principle.

Accepted Answer

According to Huygens' principle, each point of the wavefront is the source of a secondary disturbance and the wavelets emanating from these points spread out in all directions with the speed of the wave and if we draw a common tangent to all these spheres, we obtain the new position of the wavefront at a later time.
Referring to the figure,
Consider a plane wave $AB$ incident at an angle $i$ on the surface $MN$ Let $v$ =speed of the wave in the medium and $t$ = time taken by the wavefront to advance from point $B to C$
Then, $BC = v . t$
Let $CE$ be the tangent plane drawn from $C$ to the sphere, then $A E = B C = v . t$
Now, in triangles $EAC and BAC$ . We can see that they are congruent and therefore,
the angles would be equal.

This proves the law of reflection

Prove laws of reflection using Huygens' principle.

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