What is critical angle in optics?

The concept of the critical angle in optics refers specifically to the angle of incidence at which light striking the boundary between two different media will experience total internal reflection rather than refraction into the second medium. When light hits the boundary at this angle, it does not exit into the second medium but instead is entirely reflected back into the first medium.

When the angle of incidence exceeds the critical angle, no light refracts into the second medium, leading to total internal reflection, which is commonly observed in optical fibers and some lenses. This phenomenon occurs when light travels from a medium with a higher refractive index to one with a lower refractive index.

Understanding this concept is crucial for applications in optics, telecommunications, and various technologies utilizing light.