What is total internal reflection? Explain its conditions with reference to the critical angle, and describe two of its applications.

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Accepted Answer

Total internal reflection (T.I.R.) is the phenomenon in which light travelling from a denser to a rarer medium, at an angle of incidence greater than the critical angle, is completely reflected back into the denser medium instead of being refracted. The critical angle is the angle of incidence in the denser medium for which the angle of refraction in the rarer medium is exactly 90°.