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Re: induced emf again



| Why are the "two distinct phenomena" not recognized
| in our introductary textbooks? Why don't we have two
| distinct names for two distinct phenomena? Would it
| be better to say that "motional emf" is different from
| "induced emf?" How come that both emfs can be
| calculated by the same formula? Only a coincidance?
| Ludwik Kowalski

In the final analysis, both phenomena are reducible to charged particle
interactions, expressible as the effects of the fields of the "source"
charges on "recipient" charges. I tend to think of these things in this
way:
1) a stationary charged particle produces an electrostatic E field
following Coulomb's inverse square distance law;
2) a charge moving at a constant velocity also generates a magnetic B
field described by the Biot-Savart law ;
3) an accelerating charge also generates a non-conservative E field
described by Curl(E) = -dB/dt or E = -dA/dt, where A is the vector
potential (whose Curl is B);
4) the interactions of charges can be described as the effects of the
above fields on "recipient" charges through the relation:
F=q(VxB).

Our calculational language sometimes obscures this basic
particle-interaction physics.

Bob Sciamanda (W3NLV)
Physics, Edinboro Univ of PA (em)
trebor@velocity.net
http://www.velocity.net/~trebor