Snell's Law Calculator

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.

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

Snell's Law Calculator: During your academics you might be taught about the principle that light bends if it travels from one medium to another. Snell's Law Calculator over here lets you explore this topic much in detail and calculates the angle of refraction in a matter of seconds. Know what is meant by Snell's Law of Refraction, How to Calculate Angle of Refraction, Critical Angle Definition, Formula, etc.

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

n₁sin(θ₁) = n₂sin(θ₂)

  • Where n₁ is the refractive index of medium 1
  • n₂ is the refractive index of medium 2
  • θ₁ is the angle of incidence the angle between line normal to boundary between two media and incoming ray
  • θ₂ 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 θ₁ = 45°

Refractive Index of Air n₁ = 1. 000293

Refractive Index of Glass n₂ = 1.5

Formula to find Angle of Refraction using Snell's Law is given by n₁sin(θ₁) = n₂sin(θ₂)

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

1. 000293sin(45°) = 1.5sinθ₂

Simplifying further we get Angle of Refraction θ₂ = 28.1345°

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Critical Angle Formula

In the Snell's Law of Reflection you will have a scenario where sin(θ₂) 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

n₁sin(θ₁) = n₂sin(90°)

On Simplifying further we have n₁sin(θ₁) = n₂ * 1

After Simplification we can get the Angle of Incidence as Θ₁ = arcsin(n₂/n₁)

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 n₁sin(θ₁) = n₂sin(θ₂)

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.

Snell's Law Calculator