What is Snell's Law?

Snell's Law is the scientific rule that describes just how light bends while traveling from one material to another. Light is similar to a group of super-speedy race cars. When those cars zoom off from one road to another, they slow down or speed up thus changing their direction. Snell's Law helps calculate just how much they bend!

Snell's law is stated as "The ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant, for the light of a given colour and for the given pair of media".

Formula 

Snell's Law formula is given as, 

Where i is the angle of incidence and r is the angle of refraction. This constant value is called the refractive index of the second medium with respect to the first.

Following is a diagrammatic representation:

Snell's Law Formula

Snell's law formula is derived from Fermat's principle. Fermat's principle states that "light travels in the shortest path that takes the least time".

Take the refracted ray at the contact point for angles formed. Here, two different mediums with refractive indices n1 and n2 are considered through it to pass for refraction influencing. θ1 is the angle of incidence; θ2 is the angle of refraction.

Applications of Snell’s Law Formula in Real Life

Snell's Law finds everyday applications, including eye glasses and the lenses of cameras. Its principle converges light to allow for superior visualization and vision. It is also the basis of telecommunications, as every information is conducted as light over long distances in fiber optics. In addition, it deals with phenomena such as mirages and also forms an important application in medical imaging through endoscopes. Lastly, Snell's Law also has an impact on photography, lasers, and the design of telescopes that help us see inside celestial objects. Technically speaking, it is very handy in a lot of technologies and scientific applications that help us interact better with light.

Solved Problems 

Problem 1: When the ray is refracted at an angle of 14° and refracting index is 1.2, find the angle of incidence.

Solution: Given,

Angle of refraction r = 14°

Refracting index, μ = 1.2

Using the formula, Snell's law:

Angle of incidence, i = 25°

Angle of refraction, r = 32°

By making use of Snell's law formula

Problem 2: If the angle of incidence is 25° and angle of refraction is 32°, find the refractive index of the media.

Solution: Given,

Angle of incidence, i = 25°

Angle of refraction, r = 32°

Using Snell’s law formula,

 

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