Physics for IGCSE & O level - Rays And Waves (Section 11 - No. 14)
What is the critical angle?
The angle at which light is completely reflected.
The angle at which light is refracted.
The angle at which light changes color.
The angle at which light is absorbed.
Объяснение
The critical angle is the angle of incidence for which the angle of refraction is 90 degrees.