After The School
Class 12PhysicsChapter 9: Ray Optics and Optical Instruments

9.4 Total Internal Reflection

Critical angle and applications of total internal reflection.

9.4 Total Internal Reflection

When light travels from a denser to a rarer medium, if the angle of incidence exceeds the critical angle θc\theta_c, total internal reflection occurs.

sin⁡θc=n2n1=1n(if n2=1)\sin \theta_c = \frac{n_2}{n_1} = \frac{1}{n} \quad (\text{if } n_2 = 1)

Applications: Optical fibres, mirages, sparkling of diamonds.

9.3 Refraction through a Prism

Angle of deviation, minimum deviation, and dispersion of light through a prism.

9.5 Optical Instruments

Simple microscope, compound microscope, and astronomical telescope.

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9.4 Total Internal Reflection