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What is total internal reflection. Explain the phenomenon using Huygen's principle. |
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Answer» Solution :Total internal reflection: When a light ray travels from denser medium to rarer medium, the angle of incidence is greater than critical angle then it reflects into the same medium. This phenomenon is called total internal reflection. Huygen's principle : According to Huygen's principle, every POINT on the wavefront AB is a source of secondary wavelets and time during which wavelets from B reaches at C. Let `tau` be the time taken by thewave FRONT to advance from B to C. Then distance `BC=upsilon tau` In order to CONSTRUCT reflected WAVELENGTH we draw, a sphere of RADIUS `upsilon tau` from point A. Let CE represent the tangent drawn from C to this sphere. `AE=BC=vtau` Consider the triangles EAC and BAC are congruent. `therefore`Angles i and r would be equal. This is the law of reflection. 
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