In what context is the term 'critical angle' defined?

The term 'critical angle' is defined particularly in the context of reflection and refraction, which is closely tied to Snell's law. It refers to the specific angle of incidence at which light, traveling from a medium with a higher refractive index to one with a lower refractive index, will refract at an angle of 90 degrees relative to the normal line at the boundary between the two media.

When light approaches the interface at or beyond this critical angle, total internal reflection occurs, meaning all the light is reflected back into the denser medium rather than refracting into the less dense medium. This phenomenon is fundamental in various applications, including fiber optics and optical devices, making it crucial for understanding how light behaves at the boundaries of different materials.

In contrast, the other options do not pertain directly to the definition of critical angle. For instance, studying light polarization primarily focuses on the orientation of light waves rather than angles of incidence or refraction. The measurement of sound wave angles pertains to acoustics and does not involve the concepts of refraction associated with critical angle. Similarly, color dispersion relates to how different wavelengths of light are separated based on their refractive indices, which does not involve the critical angle in the same way reflection and