Final answer:
Refraction is the bending of light as it passes from one medium to another. It occurs due to the change in speed of light. This bending of light can be explained by the concept of the refractive index.
Step-by-step explanation:
Refraction is the bending of light as it passes from one medium to another, due to a change in its speed. This phenomenon occurs because light waves travel at different speeds in different mediums, causing the direction of the light to change.
The bending of light during refraction can be better understood by the concept of the refractive index. The refractive index is a measure of how much a medium can slow down or speed up light. When light rays pass from a medium with a lower refractive index to a medium with a higher refractive index, they bend towards the normal. Conversely, when they pass from a higher refractive index to a lower refractive index, they bend away from the normal. This bending of light is what gives rise to various optical phenomena such as the apparent bending of a straight object placed in water, or the formation of rainbows.
A familiar example of refraction occurs when a pencil is partially immersed in a glass of water. The pencil appears to be bent at the water-air interface because the light rays traveling from the pencil through the water into the air change direction due to refraction.
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