IGCSE Physics Practice Exam 2025 – Complete Study Resource

When the angle of incidence exceeds the critical angle, total internal reflection occurs. This phenomenon happens at the boundary between two mediums, where light travels from a more dense medium to a less dense medium. The critical angle is defined as the angle of incidence above which all the light is reflected back into the denser medium rather than being refracted through the boundary.

In this situation, the light attempts to move into the less dense medium, but due to the angle being greater than the critical angle, the light cannot escape and instead reflects entirely within the denser medium. This is crucial in applications such as fiber optics, where total internal reflection allows light to be guided efficiently along the fibers without loss.

Considering the other options, partial refraction cannot occur when the angle exceeds the critical angle, as the conditions lead to total internal reflection. Similarly, the idea that only some light passes through contradicts the definition of the critical angle, where exceeding this angle results in no refraction. Lastly, the concept of complete absorption of light does not apply here, as the light is not absorbed but rather reflected back into the denser medium.