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.

## Critical Angle Formula

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

α_c = sin^-1(n2 / n1)

αc = sin-1(n2 / n1)

• 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?

1. First, determine the refractive index of medium 1.

Measure or calculate the refractive index of the first medium.

2. Next, determine the refractive index of medium 2.

Measure or calculate the refractive index of the second medium.

3. 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.