a question about resistors in an arc experiment

"S Claus"

** With no series resistor, the current flowing in the arc would become huge and blow the fuse or circuit breaker in the supply.

.... Phil

IIRC, an arc is energized air (plasma).. Plasma is very conductive.. An arc acts like a short. Shorts can cause circuits to blow up. Resistors limit the current and keep stuff from burning out.

D from BC myrealaddress(at)comic(dot)com British Columbia Canada

Most arcs have negative resistance, so the current increases without limit, unless there is series resistance elsewhere in the circuit. Huge arc currents will blow away the electrodes or, as mentioned, blow the circuit breakers. That's fun, but doesn't last long.

I shorted a 120 volt circuit in a light fixture recently. Huge fireworks and burned-through metal. The Brat was impressed.

John

If they had negative resistance, they're be dissipating negative power. I think you mean that they have a negative resistance slope. They'll still have a positive resistance, and for a given applied potential, they'll conduct a defined current.

Syvia.

Oh, don't be a PITA.

John

Bwuahahahahaha! I liked that one, John. :-]

Tried to sneak it in there, I see...

He's funny. I liked the impression his wording gave. :-]

We just solved the energy crisis! Bwuahahahaha!

"The negative resistance characteristics of an electric arc permits the creation of a relaxation oscillator that converts direct current to radio frequency energy."

John

I wonder if a fuse has negative resistance..

delta v V2 - V1

------ = ------- = R delta I I2 - I1

But if the fuse blows at data point I2: I2 = 0 R is negative.

D from BC myrealaddress(at)comic(dot)com British Columbia Canada

John, you are losing this argument. As Syvia has already indicated, an electric arc can have a negative slope in a section of its V-I curve but the overall resistance will still be positive. The negative slope means that it has "negative resistance characteristics" but the total resistance will still be positive.

A true total negative resistor would mean that when you put a voltage across the 'negative resistor' then you would current out. I.e. the resistor would be generating power.

A negative resistor can be simulated with active circuits. In this case, the power is supplied by the power to the active circuit.

Lay off, dude. She was merely changing the statement to a more correct and accurate version. Perhaps the added info may even add to the education o sone persons (not to be named...).

** You are no judge of any such thing - asshole ** Sylvia is damn TROLL.

** Which is what he has said.

" Most arcs have negative resistance, "

** See:

Read the definition.

" However, the use of the term negative resistance to encompass negative differential resistance is more common. "

Then f*ck off.

..... Phil

The other people who replied to you are correct.

Current = Volts / resistance

A short is resistance is near zero

Thus Current = 120Volts / 0 = Infinite (huge current)

Lets say the resistance in the power wires is 0.1 ohm

then the current is = 120 / 0.1 = 1200Amp !

Joe

--
You just can\'t _stand_ to be corrected, can you? :-)

JF

He could simply have said that that was what he meant.

Except that it wouldn't support his view that the current would increase without limit.

Sylvia.

Nobody's mentioned the internal resistance in some types of power supplies.

32 years ago (+-) I had a nice 30 KV 10 ma neon sign transformer that made a fabulous big Jacobs Ladder.

40 years ago (+-) I scrounged 4 or 5 CASES (25 each) of discarded telephone company carbon zinc dry cells.

I dissected a few that were beat up, extracting the large carbon rods, and wired many of the others in series. 40 volts seemed to work good to get a really good carbon arc between the naked rods.

My main point is that batteries and transformers have an internal resistance.

What kind of line isolation are you using and what are you trying to do with the arc?

Safety warnings are not just obligatory in this case. Carbon arc presents blinding eye damage issues.. Neon sign transformer presents deadly high voltage... Your first mistake would be your last.

In article , snipped-for-privacy@austininstruments.com says...>

He wasn't corrected, simply sniped. The term "negative resistance" is part of the jargon meaning "negative incremental resistance", understanding that a passive device cannot have a negative real resistance. ...but everyone here knows that.

You love it on the _few_ occasions when you can dig at Larkin, don't you? ...but everyone knows that. Even DimBulb is with you on this snipe hunt.

--
Nope, I only dig at Larkin when, IMO, he\'s being a horse\'s ass.

Like when he refuses to admit that he\'s wrong when it\'s as plain as the
nose on his face that he is, and when he starts his silly little
name-calling when he gets annoyed. 


But if you think that everyone thinks that I like to dig at Larkin, then
why bring it up?

On a little snipe hunt yourself?

>Even DimBulb is with you 
>on this snipe hunt.

--
Oh, and by the way, fuck you.

JF