Physics Program Presents
Hidden Momentum
Friday, November 13, 2015
Hegeman 107
12:00 pm EST/GMT-5
12:00 pm EST/GMT-5
David Griffiths
Reed College
Reed College
Electromagnetic fields carry energy, momentum, and even angular momentum. The momentum density is ∊0 (E x B), and it accounts (among other things) for the pressure of light. But even static fields can harbor momentum, and this would appear to contradict a general theorem: if the center of energy of a closed system is at rest, then its total momentum must be zero. Evidently in such cases there lurks some other momentum, not electromagnetic in nature, which cancels the field momentum. But finding this “hidden momentum” can be surprisingly subtle. I’ll discuss a particularly nice example.
For more information, call 845-758-7302, or e-mail [email protected].
Time: 12:00 pm EST/GMT-5
Location: Hegeman 107