What is voltage and how to look at it intellectually?

[jim hardy]

What is voltage and how to look at it intellectually?

For me the concept of absolute potential was a breakthrough.
Hyperphysics has concise demonstrations at
http://hyperphysics.phy-astr.gsu.edu/hbase/electric/elefie.html
and
http://hyperphysics.phy-astr.gsu.edu/hbase/electric/elevol.htmlI hope following is the type of answer you sought - i sure didn't intend to "talk down".
I remember struggling with the basic concepts - with all the units named after people rather than mnemonically it's hard to keep them straight.
......................

It may help to make things a little bit visceral.

Take two good refrigerator magnets, one in each hand.
Note their attractive force when opposite poles are brought near one another
and their repulsive force when like poles are brought near

Now - you know very well electric charge acts the same way, likes repel and opposites attract. You've experienced it when removing one styrofoam cup from a stack, or the plastic bag from a wool sweater fresh from the cleaners.

Voltage is a measure of the work done in moving an electric charge over a distance against such a magnetic or electrical force.
But that's a bit foggy-----

You need to grasp the concept of potential.
Then the concept of voltage's other name, potential difference, will come clear.

Absolute Potential is the work expended against that magnetic or electrical force in moving a unit of charge from infinity to wherever it is you are.
It's simply Work = Force X Distance. Probably with an integral sign...
But that's totally impractical - who could go out to infinity to make the measurement?
So we most often see "Potential" used to mean potential energy without telling us relative to where !.

We have to settle for measuring the work required to move a charge from somewhere that's accessible to somewhere else also accessible.
That work is equal to the difference in absolute potentials between those two points --
but we needn't go clear out to infinity to measure it , just from one point to the other.
Aha - difference in absolute potentials is "Potential Difference" , the nom de plume of Voltage !
It has the units of work per unit charge, Volts = Joules/Coulomb.
Your car battery adds 12 joules(watt-seconds)of energy to every coulomb(ampere-second) of charge it delivers.
The distance is only a few inches - there's no need to go to infinity to measure it.

That is how i think 'intellectually' of voltage. But I'm not very intellectual...That's why voltmeters have two leads , and they work well despite neither lead being long enough to reach very far.
If you had a voltmeter with one test lead a quarter of a million miles long, you could measure the voltage between Earth and moon.
They've already measured the local fields there:
http://meetingorganizer.copernicus.org/EPSC2013/EPSC2013-578-2.pdf

1. Introduction
The electrostatic potential between the Moon surface and space is a key parameter that is fundamental for lunar science and human exploration on the Moon.
Many investigations of electric potential and associated electric fields have been conducted theoretically and experimentally from the surface and orbits using solar wind plasma since the Apollo era...
In summary,
high energy electron flux results in -400 V potential in the nightside of the Moon.
In the dayside, due to the photoelectron emission the surface tend to charge positively with +5–+20 V, while near the magnetic anomaly, potential more than +100 V is expected.

have fun - old jim

 

[tubeswell]

What's mica?

a silicate mineral, used for a variety of purposes including; electrical insulation, and in the production of some capacitors (i.e.; silvered mica capacitors)

 

[jeffery_winkle]

A Josephson junction consists of two superconductors separated by a thin barrier. Microwave radiation causes a quantized DC voltage to form across the junction in steps of V=f/K, where f is the microwave frequency, and K = 2e/h is the Josephson constant. A quantum voltage standard is then constructed from a series of Josephson junctions.