Re: Electrons

["J. Douglas Patterson" <dpatter@DV037S33.LAWRENCE.KS.US>]

> As electrons move through a circuit, say a battery and single resistor,
> energy is given up in the resistor as perhaps, heat or light. Now, what
> is different about these electrons after passing through the resistor
> compared with before they entered the resistor? They are not moving more
> slowly so it is not a kinetic energy situation so where does this heat
> come from?

David,

You can still use the gravity analogy with this problem.  Instead of a
mass freely falling, however, imagine a mass falling through a bunch of
fixed obsticles.  ...like a pachinco machine or a pinball machine.  The
energy the electron gives to the molecules through collisions to increase
their temperature ultimately comes from the electric field within the
wire.  The entire time the electron is making its way through the circuit,
it is being accelerated by the electric field in the wire.  As a pinball
falls down towards the flippers, the ball is constantly losing potential
energy, but it doesn't gain any kinetic energy on average due to the
frequency of the collisions.  In a similar fashion, the electron does not
gain any kinetic energy on average as it makes its way through the wire
and resistor due to the frequency of electron-molecule collisions.  The
heat produced comes from the posential energy provided by the electric
field.


        J. Douglas Patterson
        Adjunct Inst of Physics & Physical Science
        Office:  SCI 105C
        Phone:  (913)469-4444 Ext. 5947
        http://www.jccc.net/~dpatter

        "When you are courting a nice girl an hour seems like a second.
         When you sit on a red-hot cinder a second seems like an hour.
         That's relativity."     - Albert Einstein -