Final answer:
When light moves at an angle into a medium with a lower index of refraction, it undergoes refraction. The angle of refraction can be determined using Snell's Law. Total internal reflection can occur if the angle of incidence is greater than the critical angle.
Step-by-step explanation:
When light moves at an angle into a medium that has a lower index of refraction, it undergoes a change in direction. This change in direction is known as refraction. According to Snell's Law, the angle of refraction is determined by the angle of incidence and the refractive indices of the two mediums involved.
If the angle of incidence is greater than the critical angle, total internal reflection occurs. In this case, all the light is reflected back into the original medium instead of being refracted. This phenomenon is commonly observed in optical fibers.
For example, if light is moving from air (lower refractive index) to water (higher refractive index), the light will bend towards the normal (an imaginary line perpendicular to the interface between the two mediums). The extent of the bending depends on the angle of incidence and the refractive indices of air and water.
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