Snell’s Law of Refraction — lesson. Science State Board, Class 8.

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The Refraction of light rays, as they travel from one medium to another medium, obeys two laws, known as Snell’s laws of refraction.

They are given below:

The incident ray, the refracted ray and the normal at the point of intersection, all lie in the same plane.

The ratio of the sine of the angle of incidence (i) to the sine of the angle of refraction (r) is equal to the refractive index of the medium, which is a constant.

\frac{\sin i}{sIn r} = Constant = μ

Snell’s law formula is derived from Fermat’s principle,

From the diagram,

θ_{1}

\(-\) Angle of incidence

θ_{2}

\(-\) Angle of reflection

n_{1}

\(-\) Refractive index of Medium 1 (Air)

n_{2}

\(-\) Refractive index of Medium 2 (Liquid)

\begin{array}{l} n_{1} \sin θ_{1} = n_{2} \sin θ_{2} \\ \frac{\sin θ_{1}}{\sin θ_{2}} = \frac{n_{2}}{n_{1}} = Constant \end{array}

Reference:

https://commons.wikimedia.org/wiki/File:Snell%27s_Law.svg

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21. Snell’s Law of Refraction