How to Calculate Critical Angle

What is the critical angle of a light ray?

The critical angle is defined as the angle of incidence that causes light to refract along the boundary when transitioning between two media. When this angle is exceeded, total internal reflection takes place.

Does the critical angle depend on the colors (wavelengths) of light?

The critical angle is mainly dictated by the refractive indices of the two media in question and is generally independent of the light’s wavelength. Nonetheless, in certain instances, minor changes in the critical angle can be observed for different wavelengths, which can result in phenomena such as chromatic aberration.

What happens if the angle of incidence is less than the critical angle?

If the angle of incidence is less than the critical angle, refraction occurs, and the light ray bends as it enters the second medium.

What are some applications of total internal reflection?

Total internal reflection is used in fiber optics, endoscopes, and critical angle refractometers for measuring liquid refractive indices.

Can the critical angle be greater than 90 degree?

No, because it represents the angle at which the refracted ray travels along the interface between the two media.

The critical angle is a key concept in optics, especially when light interacts with boundaries between two dissimilar materials. It determines the exact angle of incidence at which light will refract along the interface between the materials, instead of entering the second medium.

In this article, how to find the critical angle of a light ray, the formula for critical angle, Snell’s law, finding a critical angle, and solve the problem.