Charge, Fields, and Motion
Date: Spring 2012
Hi, I have a few questions concerning electrons,electric fields and magnetic fields. There is an archive entry that deals with this, and some of the answers say the following.
1-When an electron is vibrating but not going anywhere, photons combine into a wave.
But, in another answer, it says:
2- Technically speaking, there is no such thing as a static electron--it will always be traveling at (or very close to) the speed of light.
Also, searching through the archives , I have read explanations which say that when a charge is still it produces only an electric field and it is only when it is moving that produces both electric and magnetic fields.
So, Can an electron be still or vibrating but not going anywhere?
And, what is a moving charge? When an electron moves, is it a moving charge?
We have to go into quantum physics to really look at this question. Photons are a divider between traditional physics and modern physics.
The traditional view is used today because it does work most of the time. It deals with the average effect of a point charge that moves like a day-to-day object would move. In this picture, an electron is a ball of charge that produces an electric field. When moving, it produces a magnetic field. When the electron oscillates, the electric and magnetic fields oscillate together to produce an electromagnetic wave. This picture does not involve photons.
The modern view works at the level of individual items, such as electrons and protons. At distances as small as the width of an atom, the traditional view does not work. Particles and waves become one thing. Light can behave as particles. Single electrons can behave as waves. Motion becomes uncertain. An object can be two places at once, arriving where it is going before it leaves where it started. In the modern view, we have photons. Every object, even an electron, has a wavelength and a frequency. Frequency relates to energy and wavelength relates to momentum.
Photons are always flying around from charge to charge. This is what “tells” the charges about each other. This is what transfers energy and momentum from charge to charge. The average transfer of energy between charged objects is what we call force. When enough charge exists to produce a field of photons we can measure, we interpret this as electric and magnetic fields. For a body of charge that has little average motion and no organized patterns within, the magnetic properties of the photons will average out, leaving only the electric field to measure. When the net charge is zero but there is organized motion within, the electric effects can average out, leaving only a magnetic field.
When the motion is an oscillation, both electric and magnetic properties within the photons have effect. The photons take on the appearance of electromagnetic waves. It is this averaging effect that makes the randomness of quantum physics become the organization of the tradition physics. Traditional physics is much easier to work. It matches reality quite well, so long as you do not get too small (quantum) or too fast (relativity). This is why traditional physics continues to be used with great success.
Dr. Ken Mellendorf
Illinois Central College
Good questions, it appears that you need some clarification. It is not always going to be very clear and responsive to rules: electrons exhibit quantum electrodynamic(QED) behavior. QED can be quite interesting phenomena.
The electron, e-, is always moving. They are freely exchangeable with the e- of any other atom. Moving e- are moving electronegative charges and create a moving dipole local environment. E- are capable of moving from one place and time to another place and time.
The net charge may be cancelled by a proton, but the e- local environment is almost always electronegative.
Please be wary of getting so lost in delineating the details that you may forget the overall: it is not "black and white", there are few boundaries... the charges are relative to the environment the e- happens to be in AND they may take on wave characteristics!
Keep your e- movin', movin',,,
Peter E. Hughes, Ph.D. Milford, NH
Click here to return to the Physics Archives
Update: June 2012