Light and sound is found everywhere. Light and sound waves travel from place to place and can be seen and heard. Light is visible to the human eye and is responsible for the sense of sight. It is a form of energy we can see when it is reflected off the surface of an object.

    Light Waves travel through the air from place to place and do not carry matter. Light is believed to travel faster than anything in the universe. It travels at a speed of 186,000 miles per second. Light is unable to travel through solids, but it can travel through liquids and gases.

    There are two properties of light. The first property of light is called reflection. Reflection is when light bounces off a surface which then allows the object to be visible to the eye. For example, when the moon is seen in the sky. it is because the light from the sun reflects off the surface of the moon. A light ray comes off a surface at an equal angle to the angle at which it struck the surface. The second property of light is called refraction. Refraction is when a ray of light passes from a transparent medium to another transparent medium such as front air to water. it changes speed and the way it bends. 

What is the main idea of the paragraph three?