Waves Page 25
"Wave" is a very useful word. You can wave hello, you can wave goodbye, you can wave your hair, or you can surf a wave in the ocean. But in science, the word "wave" means the motion of something, and the motion could be up & down, or from side to side. Examples include an electrical wave, a heat wave, and a radio wave. The speed that the wave is moving is called its frequency, and that is a measure of the number of ups and downs that pass by a given point within a given period of time. Electrical wave is the alternative current (up & down) of an electric charge. Heat waves can be seen rising from a hot object.