pg 1 next
This text is meant to accompany class discussions. It is not everything there is to know about energy. It is meant as a  prep for class. More detailed notes and examples are given in the class notes, presentations, and demonstrations linked below under unit resources.
Click here for questions that go along with this energy section.


When a charge ACCELERATES it creates a magnet field. When the magnet field is created an electric field is created perpendicular to the magnetic field. The Electric and magnetic field look like the ones shown below.

(Image by SuperManu (Self, based on Image:Onde electromagnetique.png) [GFDL (, CC-BY-SA-3.0 ( or CC BY-SA 2.5-2.0-1.0 (], via Wikimedia Commons)


This is an application of the open palm right hand rule where the electric field is the thumb, the magnetic field are the fingers the the palm is the force pushing the wave along in the velocity's direction.

These two waves are actually one wave called an electromagnetic wave. This also referred to as electromagnetic radiation. You probably refer to electromagnetic waves as "light." All of the wireless devices in your house produce light. We can't detect their frequencies, (or colors,) with our eyes. Instead we have to use devices like, phones, radios or blue tooth receivers to "see" their colors. Infrared remotes use a frequency of red light that we can't detect with out help. However, your smart phone can see them.


Activity to do with your smart phone
Set your smart phone up or any digital camera to take a video. Find a TV remote, they are usually infrared remotes. Point the remote at the camera lens while pointing pressing the power button on the remote. Take a moment and try it. If your camera has a high speed mode, try looking at the remote in this mode. (This also works with any digital camera including your laptops camera.)


There two ways of observing an ACCELERATING charge.

(1) Change direction. A charge the moves perpendicular to a magnetic field curves. This is a change in direction.

(2) A charge that changes speed.

The positive charge above is traveling across two boxes, "A" and "B." Which box will emit a wave of electromagnetic radiation?


Previous page Main Unit Page

by Tony Wayne ...(If you are a teacher, please feel free to use these resources in your teaching.)