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What gives electricity its heat?


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Resistance(Joule Heating) and the thermoelectric effect.

 

Thermoelectric effect would be what you'd want to look into if you want cooling. Peltier coolers and the like.

Edited by Endy0816
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The electrons transfer some of their energy by colliding with the atoms in the lattice, thus transferring energy to the atoms to make them move. This causes heat.

The equation for the increase in heat energy is

Q = I2Rt

Where Q is the heat energy from the electricity, I Is the current, t is time, and R is the resistance of the wire.

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The electrons possess energy. When these electrons are transferred through a medium, it is not necessary that the medium is a superconductor, and when it is not, some electrons collide with particles of the conductors and thus give heat-due to Resistance and the law of conservation of energy.

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The electrons possess energy. When these electrons are transferred through a medium, it is not necessary that the medium is a superconductor, and when it is not, some electrons collide with particles of the conductors and thus give heat-due to Resistance and the law of conservation of energy.

Ok so the amperes from electricity is due to collisions with the lattice. But if something has a high resistance, like say glass, how would I get a steady current to even flow through solid glass in the first place considering glass has a really high resistance?

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There's conductive glass if that's what you are talking about. Could also pass current via electromagnetic fields.

 

Are these questions stemming from a goal or project?

That's not what I mean. Resistance means the ability to resist the flow of an electrical current right? So if tungsten is highly resistant, how does electricity flow through it at all enough to light up a light bulb at all?

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The tungsten filament in an incandescent light bulb is specifically rated for a given voltage, e.g. 120 volts, 230 volts etc. By not exceeding this limit the filament will achieve its designed power rating of wattage, e.g. 60 w, 75 w etc. without premature failure. By staying below tungsten's melting point of 3,695 K (6,191 °F) the proper electric current will heat the filament to between 2,000 - 3,300 K (3,140 - 5,480 °F)

 

The specific resistance that the tungsten has to the rated voltage determines the current that causes the filament to emit light energy, but most of this energy is given off as heat. A lower voltage will increase bulb life. For example, by operating a 120 volt 60 watt bulb at 100 volts or less you will increase the bulb's life expectancy greatly. This is an old sign company trick to make those hundreds if not thousands of flashing lights on those old Las Vegas type signs last longer, they ran the bulbs at a lesser voltage to achieve the benefit of longer bulb life, saving a lot of money in maintenance costs.

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Ok so the amperes from electricity is due to collisions with the lattice. But if something has a high resistance, like say glass, how would I get a steady current to even flow through solid glass in the first place considering glass has a really high resistance?

 

There are, broadly, two classes of materials: metals/conductors and non-metals/insulators (well, three if we include semiconductors).

 

In metals, there are many free electrons that can carry the electric current. The resistance of different metal varies so, to get the same current, you need to provide more voltage. Voltage times current equals power: this is where the energy for the heat comes from. (Apologies to the purists for horribly mangling the units there in the cause of simplicity!)

 

In a non-conductor, like glass, there are few free electrons and so current doesn't flow (until you provide so much voltage that the material breaks down).

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The specific resistance that the tungsten has to the rated voltage determines the current that causes the filament to emit light energy, but most of this energy is given off as heat.

 

It's all given off as heat. It's just that some of that radiation is in the visible part of the spectrum.

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  • 3 weeks later...

electrons are tiny little point like particles that collide with other little point like particles giving off point-like particles called photons.

 

Since this is the usual point of view we should never point out that the probability that a finite number of moving points colliding with other points on a 3D manifold is zero.

Edited by decraig
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electrons are tiny little point like particles that collide with other little point like particles giving off point-like particles called photons.

 

Since this is the usual point of view we should never point out that the probability that a finite number of moving points colliding with other points on a 3D manifold is zero.

I agree. We should never bring up wrong and/or irrelevant stuff. Did you have a point?

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Ok so the amperes from electricity is due to collisions with the lattice.

??

 

1 Amper * 1 second is 1 Coulomb.

 

1 C / e = 1 C / 1.602*10^-19 C = 6.25*10^18

 

1 C = 6.25*10^18 electrons.

 

so

1 A = 6.25*10^18 electrons per second.

 

But if something has a high resistance, like say glass, how would I get a steady current to even flow through solid glass in the first place considering glass has a really high resistance?

It's a matter of Voltage. Dielectric can pass electrons with high enough kinetic energy.

 

Read more here

http://en.wikipedia.org/wiki/Electrical_breakdown

 

"Electrical breakdown or dielectric breakdown refers to a rapid reduction in the resistance of an electrical insulator when the voltage applied across it exceeds the breakdown voltage. This results in a portion of the insulator becoming electrically conductive. Electrical breakdown may be a momentary event (as in an electrostatic discharge), or may lead to a continuous arc discharge if protective devices fail to interrupt the current in a high power circuit."

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