The physics of the eye is fascinating. Objects are seen when light is emitted or reflected from them and enters the eye through the pupil.
At the back of the eye is the retina which consists of light sensitive cells which send a message to the brain via the optic nerve. So when we see, light waves enter the eye and stimulate the cells of the retina which send an electrical signal to the brain which then decodes this signal.
This can be looked up in any physics or, possibly biology text book.
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ContentsSight, Safety, Light needs a source, Speed of Light