Light
From Wikipedia, a free encyclopedia written in simple English for easy reading.
Light is a form of energy. Anything with a temperature above absolute zero emits (gives off) light. Light is also called "electromagnetic radiation". Light is made up of tiny particles called photons.
Light moves at the speed of light, about 300,000 km per second. This means it takes about one second for light to reach Earth from the Moon.
Light moves in a straight line, creating shadows when the path of light is blocked. More solid things will have a dark shadow, things that are more clear have a lighter shadow, and transparent things will have none or very little shadow.
Our eyes react to light; when we see something we see the light it reflects, or the light it emits. For example, a lamp gives off light, and everything else in the same room as the lamp reflects its light.
Every colour of light has a different wavelength. The shorter the wavelength, the more energy the light has. All light moves at the same speed, no matter how much energy it has, except when going through a partly clear object, but the speed difference is still very small.
White light is made up of many different colors of light added together. When white light shines through a prism, it splits up into different colors, becoming a rainbow. The rainbow contains all of the wavelengths of light that we can see. Red light has the longest wavelength, and purple, or violet, light has the shortest.
Light with a wavelength shorter than violet is called ultraviolet light. Light with a wavelength longer than red is called infrared light. Radio waves are a form of light with a wavelength even longer than infrared light. The microwaves that are used to heat food in a microwave oven are also a form of light. Our eyes cannot see those kinds of light, but there are some cameras that can see them.
