A Level Physics Practice Exam

Which phenomenon occurs when light travels through different refractive indices?

1. Reflection

2. Diffraction

3. Total internal reflection

4. Scattering

The correct answer is: Total internal reflection

The phenomenon that occurs when light travels through different refractive indices is total internal reflection. This happens when light moves from a medium with a higher refractive index to a medium with a lower refractive index, at an angle greater than the critical angle for the two materials. At this point, rather than passing into the second medium, the light is completely reflected back into the first medium. Total internal reflection is a critical concept in optics and is the underlying principle that allows optical fibers to transmit light over long distances with minimal loss. When light travels from glass (which has a higher refractive index) into air (which has a lower refractive index), if the incidence angle exceeds this critical angle, the light does not refract but is instead reflected back into the glass at the boundary. In contrast, reflection typically involves light bouncing off surfaces without the specific criteria related to refractive indices. Diffraction refers to the bending of waves around obstacles, which does not inherently involve changes in refractive indices. Scattering is a different process where light is absorbed and re-emitted in different directions, which also does not focus on the behavior at the interface of materials with different refractive indices. Thus, total internal reflection distinctly describes the behavior of light based on varying