Chronology Current Month Current Thread Current Date [Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

# Re: definition of voltage

• From: "John S. Denker" <jsd@MONMOUTH.COM>
• Date: Sat, 2 Jun 2001 18:52:14 -0400

I said voltage was
> the part of the energy
[per unit charge]
> due solely to
> the interaction of the particle's charge with the applied field.

At 02:37 PM 6/2/01 -0400, Eugene Mosca wrote:
What is the energy of the interaction of the particle
with the applied field? If kinetic energy is neglected then it seems to me
the only other energy is electrostatic potential energy.

Nope.

The meaning becomes clearer if we use the term in a sentence, such as:
The voltage drop along this path is 17 milliVolts.

Example 1: Take a test charge, attach it to a crank, and crank it along
the path. When it gets to the end of the path, there will have been an
energy transfer of 17 milliJoules per Coulomb.

The energy is transferred from the field to the particle, and thence (in
this example) to the crank.

This is a powerful and quite general idea. It applies to potential
voltages as well as non-potential voltages.

Example 2: In a betatron, the energy is transferred from the field to the
particle, and (mostly) stays with the particle in the form of kinetic energy.

But the basic idea is the same: the energy transfer is 17 milliJoules per
Coulomb, as the particle moves from end to end of the given path. That's
what we mean by 17 milliVolts.