Re: Explaining

[Raacc@aol.com]

In a message dated 98-02-19 15:16:31 EST, you write:

<< >Well, I've had many undergraduates who will respond to a question testing
> this concept, saying that they believe that resistors heat up because the
> electrons lose kinetic energy when passing through the resistor, which is
> the same as saying they go in faster than they come out. I would have
> thought they'd not respond this way if they really grasped the continuity
> equation, or Kirchoff's laws. >>

What is the present model for this?  The model I learned delt with average
drift velocity.  The electric field accelerated electrons locally, and when
these electrons interacted with the lattice, their kinetic energy was reduced,
increasing the lattice energy.  Of course, on average, the drift velocity
remained constant unless the electric field was changed, or the change in
lattice energy caused a change in its resistance to electron flow.  I don't
see how localized acceleration, then loss of kinetic energy in interactions
with the lattice,  means that on the average electrons entered the resistor at
a faster speed than leaving it.

Bob Carlson