Higher harmonic detection employing wavelength modulation spectroscopy and near infrared diode lasers: An undergraduate experiment
Frequency modulation and harmonic detection are extensively employed in a variety of experimental techniques and offer a detection sensitivity limited only by quantum noise. We discuss a simple experi...
Frequency modulation and harmonic detection are extensively employed in a variety of experimental techniques and offer a detection sensitivity limited only by quantum noise. We discuss a simple experi...
Mechanics of two pendulums coupled by a stressed spring
The mechanics of two pendulums coupled by a stressed spring is discussed, and the behavior for small oscillations is described. When the system is in its highest symmetry configuration, the pendulums ...
The mechanics of two pendulums coupled by a stressed spring is discussed, and the behavior for small oscillations is described. When the system is in its highest symmetry configuration, the pendulums ...
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Hidden momentum, field momentum, and electromagnetic impulse
American Journal of Physics -- September 2009 -- Volume 77, Issue 9, pp. 826-833
Issue Date: September 2009
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Electromagnetic fields carry energy, momentum, and angular momentum. The momentum density, 
0(E×B), accounts (among other things) for the pressure of light. But even static fields can carry momentum, and this would appear to contradict a general theorem that the total momentum of a closed system is zero if its center of energy is at rest. In such cases, there must be some other (nonelectromagnetic) momenta that cancel the field momentum. What is the nature of this “hidden momentum” and what happens to it when the electromagnetic fields are turned off?
©2009 American Association of Physics Teachers
0(E×B), accounts (among other things) for the pressure of light. But even static fields can carry momentum, and this would appear to contradict a general theorem that the total momentum of a closed system is zero if its center of energy is at rest. In such cases, there must be some other (nonelectromagnetic) momenta that cancel the field momentum. What is the nature of this “hidden momentum” and what happens to it when the electromagnetic fields are turned off?
©2009 American Association of Physics Teachers
| History: | Received 1 February 2009; accepted 20 May 2009 |
| Permalink: | http://dx.doi.org/10.1119/1.3152712 |