Gujarat BoardEnglish MediumSTD 12 SciencePhysicsWAVE OPTICS2 Marks
Question
Write limitations of Huygen's Principle.
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Answer
→ Following is the limitation (short coming) of Huygen's principle:
→As per Huygen's principle, we get two wavefronts : one, in the direction of propogation of the wavefront (forward) and second, in the backward direction of the wavefront. They are shown in the fig. with $G_1 G_2$ and $D_1 D_2$. →But we get wavefront only in the forward direction, and not in the backward direction. This is the limitation of Huygen's principle. → To explain this, Huygen argued that the amplitude of the secondary wavelets is maximum in the forward direction and zero in the backward direction. →By making this adhoc assumption, Huygens could explain the absense of the backwave. →However, this adhoc assumption is not satisfactory and the absence of the back wave is really justified from more rigorous wave theory.
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