Snell's Law

Snell's Law describes how the direction of light changes when it moves from one medium to another. What Snell's Law says is that when light moves from a medium with a high index of refraction to a medium with a low index of refraction it will bend away the normal of the plane dividing the two media. Conversely, when light moves from a medium with a low index of refraction to a medium with a high index of refraction it will bend towards from the normal dividing the two media.

The two forms of the law are:

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$v_{1}\sin {\theta _{1}}=v_{2}\sin {\theta _{2}}$

where:

Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle n_1} and Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle n_2} are the indices of refraction in media 1 and 2, respectively

Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle v_1} and Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle v_2} are the speeds of light in media 1 and 2

Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \theta_1} and Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \theta_2} are the angles measured from the normal and the respective ray.

The index of refraction of a material is inversely proportional to the speed of light in that material, i.e. light will move slower in a material with a high index of refraction than it will in a material with a low index of refraction.