Final answer:
Light refracts when it passes from one medium to another and is determined by Snell's law. When light strikes a mirror, it reflects with the angle of incidence being equal to the angle of reflection.
Step-by-step explanation:
Light refracts when it passes from one medium to another. Refraction occurs because light travels at different speeds in different mediums, causing the light rays to change direction at the boundary between the two mediums. The change in direction is determined by Snell's law, which states that the ratio of the sine of the angle of incidence to the sine of the angle of refraction is equal to the ratio of the velocities of light in the two mediums.
For example, when light passes from air into water, it slows down and bends towards the normal line, causing the light to refract. This can be observed when placing a pencil partly in a glass of water - the pencil appears to be bent at the water-air interface.
Another example is when light strikes a mirror and reflects. Although refraction is not involved in this case, it is important to note that the angle of incidence of a light ray striking a mirror is equal to the angle of reflection, according to the law of reflection.
Learn more about Refraction of light