1What is light?
Light is a form of energy. This energy is called electromagnetic energy because it is made up of changing electric and magnetic fields. When the majority of people talk about light, they generally mean light that can be seen by humans. However, there are many other kinds of light that humans cannot see. Together, all the different types of light make up the electromagnetic spectrum. The tiny part of the electromagnetic spectrum that humans can see is called the visible light spectrum.
Just as waves in water ripple out from their source, light can be thought of as a wave that spreads out in all directions from a light source, such as the Sun or a light bulb. The light gets dimmer as it moves farther away from the source.
Light waves travel or radiate along straight lines is called rays. Rays can be seen when sunlight shines through a small gap between clouds. This process is called radiation.