Law of Refraction

Chapter-9|Ray Optics and Optical Instrument|NCERT 12th Physics:

Law of Refraction:

First Law:- The incident ray, the refracted ray and the normal to the refracting surface at the point of incidence, all lie in the same plane.

Second Law(Snell’s Law):- The ratio of the sine angle of incidence to the Sine angle of refraction is constant for the two given media. This constant is denoted by ¹μ₂ and is called relative refractive index of medium 2 with respect to medium 1.


Critical Angle:

The angle of incident in denser medium for which angle of refraction in rarer medium is 90⁰ called Critical Angle.

The value of critical angle depends on the nature of two media in contact.
According to Snell’s Law


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