Enter the refractive index in medium 1 and the refractive index in medium 2 into the calculator. The calculator will evaluate and display the critical angle.

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## Critical Angle Formula

The following equation is used to calculate the critical angle through two mediums.

α_c = sin^-1(n2 / n1)

α_{c} = sin^{-1}(n_{2} / n_{1})

- Where Ac is the critical angle
- n1 is the refractive index in medium 1
- n2 is the refractive index in medium 2

To calculate a critical angle, take the inverse sine of the ratio of the refractive index of the second medium over the refractive index of the first medium.

## Critical Angle Definition

A critical angle is an angle described by snells law that is a measure of the refraction of light through different mediums.

## Critical Angle Example

How to calculate a critical angle?

**First, determine the refractive index of medium 1.**Measure or calculate the refractive index of the first medium.

**Next, determine the refractive index of medium 2.**Measure or calculate the refractive index of the second medium.

**Finally, calculate the critical angle.**Using the formula above calculate the critical angle.

## FAQ

**What is a critical angle?**

A critical angle is the angle between the light that travels through two different mediums.