Light normally travels in straight lines until they are in contact with another material. When this happens, light bends (changes direction and travels in another straight line), the bending is known as refraction. This happens because light travels in different speed with different materials. For example, if light travels through air and hits a dense material such as water, the light slows down and bends into the more dense material. Light rays moving from a less dense material will speed upwards and outwards. This is called reflection.
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Understanding Shadows |
An object that doesn't allow any light to pass through will create a shadow. If light shines onto an opaque object, the light will travel to the side of the object, this forms a shadow. Light only travels in a straight line. A transparent object will not make a shadow as the light rays will just pass through it.
Why are shadows dark? This is because of something called Rayleigh scattering. |