You know…the little blue arc that shocks the hell outta ya and causes people to pull an orange robe buddhist at the gas station?
Why doesn’t it burn ya? Too short a timeframe? I’m thinking it’s gotta be a couple thousand degrees…
Thanks in advance.
It’s an electric arc, not a flame. When something resists the flow of electric current (which pretty much everything except for superconductors do) then the energy gets converted into heat. The flow of electricity in a shock like that is too short and contains too little energy to heat up things noticably. A lightning bolt, on the other hand, is exactly the same thing on a much bigger scale. Most of the damage done to people by a lightning bolt is burn damage, and many forest fires and brush fires are started as a result of a lighning strike every year.
Electric arcs like what you describe are typically a discharge of several thousand volts (probably between 10,000 and 80,000 volts if you can see the spark) but very low current. Your stove cooks with a much lower voltage, but a much higher current. Much more energy gets transferred to the heating element because of this. Lightning is several million volts with several hundred thousand amps of current, which is so much energy that it can cook darn near anything despite being such a short duration.
Your fingers do get heated up slightly during a static discharge, but not enough to really be noticable. The pain comes from your nerve’s responses to the electricity flowing directly down through your nervous system.
Yeah…but WHAT"S THE TEMPRATURE… you just said it’s converted to heat? How hot is a spark?
It’s only converted to heat in the presence of high resistance, which you don’t have. The spark that makes you jump doesn’t really have a temperature.
Perhaps a clarification is in order.
The temperature of an object is essentially a measure of the average kinetic energy of its molecules. A spark contains no molecules, and therefore has no temperature.
He’s referring to the wild dancing performed by some Buddhist sects and the Hare Krishnas (which may or may not be Buddhist, I don’t know).
He’s probably referring to the famous picture of a monk who burned himself alive at a gas station in protest of something or other.
I think the picture is on the first RHCP CD (or this is another flaming monk)
That would be RATM (Rage Against the Machine) not RHCP (Red Hot Chili Peppers). I feel so stupid.
Along the same lines…
Is the tiny “crackle” associated with a spark just a miniature thunderclap? If it is, that suggests that the air is heated for a moment, causing a small “boom.”
This is the most well known shot of the incident, with the gasoline canister next to him and the car in the background.
A spark contains no molecules, granted…it’s a shifting of electrons… are you saying that electrons in a spark have no temperature?
Does the energy only get converted to light then? Not temperature?
Right, by orange robed buddhist, I was referring to the recent spate of news articles where people have blown themselves up accidentally by static discharge while filling up their cars at gas stations…
Splanky has the right pic I was referring to.
I don’t know about a spark but they have certainly measured the temperature of lightning which averages around 30,000 K (or about 53,000 F).
Given that lightning and sparks are essentially the same thing just on different scales I would assume sparks have a temperature as well.
Ok…getting closer here…
The temperature of a spark in a spark plug is around 800-900[sup]o[/sup] C. (Cite: http://www.sciencenet.org.uk/database/Technology/9609/t00171d.html )
I’ll grant that a spark from a spark plug is a lot juicier than what you get off your light switch after shuffling over the carpet but I can’t find a cite for a ‘normal’ spark (yet).
At 900 to 900 degrees centrigrade, is that considered plasma? Are sparks just itty bitty bits o plasma then?
SUperheated gas, ionized electrons = plasma right? Is that what makes the light?
Soo…right now we we figure it’s somewhere between 0 and 53,000 F.
A spark is not “electricity”, instead it is composed of nitrogen and oxygen molecules which have turned into plasma. You can’t have sparks in vacuum, vacuum is a perfect insulator.
I’ve looked at my skin under a microscope after zapping myself with “static” sparks. The spark produces a tiny white spot on the skin. It’s probably a burn mark, since skin has fairly high resistance, and the value of electric current during the spark is fairly immense. Also, the resistance of the white spot is lower than the surrounding skin, so once a spark has made its mark, later sparks will tend to “jump” to that same spot on your finger.
Spark temperature is more than enough to ignite flammable vapors. If your house has an electric stove, you might not know that modern gas stoves don’t have “pilot light” flames, instead the gas burners are ignited with a high voltage spark generator.
Vacuum isn’t a perfect insulator. You can quite easily get current to flow through a vacuum, but you would call it an electron beam or a pseudospark, rather than a spark.
What would an electron beam/pseudospark look like?
An electron beam doesn’t look very interesting. No photons are involved, so you can’t see it.
The CRT in a computer monitor uses an electron beam. Nothing visually interesting happens until the electrons hit the phosphors on the screen.