Created By : Naaz Fatima

Reviewed By : Rajashekhar Valipishetty

Last Updated : May 18, 2023

Snell's Law Calculator is a free tool that describes the angle of refraction using the Snell's Law Formula in a fraction of seconds. All you have to do is provide the inputs in the specified input fields and hit the calcuate button to avail results in no time.

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Refractive index 2 (n₂):
Angle of incidence (θ₁):
Angle of incidence (θ₂):

Snell's Law of Refraction

Snell's Law describes how refraction works. If a light ray enters different medium then its speed and wavelength changes. The ray bends either towards or away from the media boundary. Angle of Refraction depends on the indices of refraction of both media.

Snell's Law

nΓéüsin(╬╕Γéü) = nΓéésin(╬╕Γéé)

  • Where nΓéü is the refractive index of medium 1
  • nΓéé is the refractive index of medium 2
  • ╬╕Γéü is the angle of incidence the angle between line normal to boundary between two media and incoming ray
  • ╬╕Γéé is the angle of refraction the angle between normal to boundary and ray travelling through medium 2

Snell's Law is valid for isotropic media. For anisotropic ones such as crystals the ray gets splitted into two.

Snell's Law Example


Find the Angle of Refraction of Light Beam that Passes from Air to Glass? If the Angle of Incidence is 45┬░, refractive index of air is 1. 000293, and refractive index of glass is 1.5?


Given that

Angle of Incidence ╬╕Γéü = 45┬░

Refractive Index of Air nΓéü = 1. 000293

Refractive Index of Glass nΓéé = 1.5

Formula to find Angle of Refraction using Snell's Law is given by nΓéüsin(╬╕Γéü) = nΓéésin(╬╕Γéé)

Substituting the input values in the above formula we have the equation as follows

1. 000293sin(45┬░) = 1.5sin╬╕Γéé

Simplifying further we get Angle of Refraction ╬╕Γéé = 28.1345┬░

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Critical Angle Formula

In the Snell's Law of Reflection you will have a scenario where sin(╬╕Γéé) is greater than 1. This is because all the light is reflected from the boundary and the phenomenon is known as Total Internal Reflection.

The Highest Angle of Incidence for which the light doesn't reflect is known as Critical Angle. Refracted ray travels along the boundary between both media and the angle of refraction is 90┬░. Applying this we will have the critical angle equation as follows

nΓéüsin(╬╕Γéü) = nΓéésin(90┬░)

On Simplifying further we have nΓéüsin(╬╕Γéü) = nΓéé * 1

After Simplification we can get the Angle of Incidence as ╬ÿΓéü = arcsin(nΓéé/nΓéü)

FAQs on Snell's Law Calculator

1. How do you find the Angle of Refraction using Snell's Law?

Angle of Refraction can be calculated using the Snell's Law Formula nΓéüsin(╬╕Γéü) = nΓéésin(╬╕Γéé)

2. What is n1 and n2 in Snell's Law?

n1 and n2 are the refractive index of medium 1 and medium 2 respectively.

3. In Which Case Snell's Law is not Applicable?

Snell's Law is not applicable if the angle of incidence is zero as the angle of refraction will also be zero.

4. What is Snell's Law for?

Snell's Law is a formula that describes the relationship between angle of incidence and refraction if light or other waves passes through a boundary between two isotropic media.