Is a negative rail really NEGATIVE?

Electrical Engineers think a positive test charge so that "current" flows from positive terminal to negative.

Only Physicists fret over electrons and other such confusing definitions ;-) ...Jim Thompson

"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...

In my first electronics class (junior high school) I built a power supply and had the red binding post as the negative side of the supply. Before hooking up his Simpson vom, my teacher asked me about the polarity and then scolded me when he found out that I had it hooked up backwards.

I remember answering that it was the electrons that were the things that moved so they're the source of the electricity and should be the "hot" side. It took me a while to adopt the conventional current flow mindset. I'm still not quite over it some 40 years later.

Bob

Absolute charge exists, in the sense that a negative body has more electrons than protons. As a practical matter, that's basically impossible to measure. Engineers use relative potential, where we pick something (like a chassis, or the body of a car, or a rod stuck in the Earth) and we call that zero volts. That's the thing you clip the black wire of your DVM to.

It's not clear to me that Earth is neutral in the absolute electron/proton balance sense. I've heard the argument that it is, but it's not entirely convincing.

John

It sounds pretty smoky to me.

And there is less difference between that 24VDC power supply and the battery than you'd like to think. A battery is just an electrochemical device that acts as a pump for electrons, working to move them from its positive terminal to its negative terminal. A transistor/rectifier/capacitor style power supply is just an all electronic device that acts as a pump for electrons, working to move them from its positive terminal to its negative terminal.

In neither case are electrons created, destroyed, pulled out of the ass of the patron saint of electricity, or otherwise changed in number.

if Ben Franklin had guessed the other way, there wouldn't be a problem.

-- Les Cargill

Is the solar wind neutral? I'd guess it is, doesn't take too much charge imbalance to over come gravity.

But the Sun could have potential a lot different from the Earth. (I think)

George H.

The only time it really makes a difference is when you rub a balloon in your hair and stick it to the wall. ;-)

For anything else, just invert all of the signs. The arrows on diodes point in the direction of hole flow.

The thing I still don't understand is how the crt screen knows exactly which hole to throw out of the phosphor, on a trajectory that exactly matches the electric and/or magnetic fields through the deflection plates/coils/ion trap, to land exactly on the tip of the field emission cathode. ;-)

Cheers! Rich

It'd be a _terrible_ problem! Then the charge carriers would be positrons, and we'd all be made of antimatter! =:-O

;-) Rich

Like the diode, they just follow the arrows.:)

good one. And "in mid-air" too! :-)

No, the solar wind has a non-uniform charge. The northern lights follow magnetic field because of the positively charged particles being grouped away from neg. solar wind sectors. A FULL ACCOUNTING REVEALS CHARGE NEUTRALITY.

Which way does Lightning ALWAYS travel?

And yes, it IS always the same way.

If the air gets too 'negative' the ground will suck it away eventually!

I find that a very funny remark.

It would make a great test for up-n-comers at a bar.

Damnit, Jim! I'm a surgeon, not a aaaaaaaaaaaa..........

y!

I'm not sure what you're getting at, but there is cloud to ground, ground to cloud, cloud to cloud, positive and negative lightning.

Les Cargill expounded in news:isp166$tkn$ snipped-for-privacy@dont-email.me:

...

And he had a 50% chance of getting it right!!

I suppose he came out ok on the lightning experiment.

Warren

Look it up on wikipedia. You are AlwaysWrong.

John

Long term, it ought to be, otherwise the sun would build up an increasing potential, which would suck back the opposite charges.

But that doesn't mean that Earth is neutral. I suppose some satellite in an elliptical orbit could measure gradients. I don't know if that's been done.

Could be.

John

You have plus and zero! If you want negative you need a second battery in series.