- #1
yyouth24
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Why does passing current through Wolfram filament, heats the Wolfram filament in light bulb? What happens with the electrons?
Why Does Passing Current Heat Wolfram Filament in Light Bulb?
- Thread starter yyouth24
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In summary, the Wolfram filament releases more energy than the iron when current is passed through it, which is why it heats up in a light bulb. The electrons collide with the ions of the filament, and pass on its kinetic energy to the ions in the form of heat energy, which is proportional to the square of the current multiplied by the resistance of the filament.
- #2
Archduke
- 59
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It's down to Ohmic heating. The electrons collide with the ions of the filament, and pass on its kinetic energy to the ions in the form of heat energy, which is proportional to the square of the current multiplied by the resistance of the filament.
- #3
yyouth24
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And why let's say, the Wolfram filament is releasing more energy (when current passes through it) than the iron?Archduke said:
- #4
Danger
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Welcome to PF, Yyouth.
First off, thank you too much for driving me half nuts with your question. :grumpy: (
) I spent a couple of hours trying to figure out who the hell Wolfram was and how his filament differed from a normal tungsten one.
Anyhow, tungsten is a lot denser than iron, so internal particle collisions are far more numerous. Its other properties, though, are what make it so incredibly perfect for lightbulb use. To start with, it has one of the highest melting points of any metal. Combined with its very low thermal expansion coefficient, it allows bulbs to be run far hotter than could be achieved with other materials. That low expansion also allows a very long piece of wire to be put into a very small space. Filaments are typically double-coiled, wherein the original coiled wire is coiled again. The easiest way that I can think of to clarify that is if you were to take a long spring such as from a ball-point pen and wrap it around a toothpick. That 1/4" long filament would probably be over a metre long if stretched out. Tungsten is also very unreactive, so impurities that might sneak into the argon atmosphere of a bulb are less likely to cause failure.
First off, thank you too much for driving me half nuts with your question. :grumpy: (
) I spent a couple of hours trying to figure out who the hell Wolfram was and how his filament differed from a normal tungsten one. Anyhow, tungsten is a lot denser than iron, so internal particle collisions are far more numerous. Its other properties, though, are what make it so incredibly perfect for lightbulb use. To start with, it has one of the highest melting points of any metal. Combined with its very low thermal expansion coefficient, it allows bulbs to be run far hotter than could be achieved with other materials. That low expansion also allows a very long piece of wire to be put into a very small space. Filaments are typically double-coiled, wherein the original coiled wire is coiled again. The easiest way that I can think of to clarify that is if you were to take a long spring such as from a ball-point pen and wrap it around a toothpick. That 1/4" long filament would probably be over a metre long if stretched out. Tungsten is also very unreactive, so impurities that might sneak into the argon atmosphere of a bulb are less likely to cause failure.
- #5
Cundo007
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Hey.. this not a reply because I am new i this forum... i need help... how can i post a questions... sorry for the trouble...
- #6
Danger
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Welcome to PF, Cundo.
Go to the appropriate sub-forum (Classical Physics is this one). Just above the main body, there's a button that says 'New Thread'. Click on that, and you'll be prompted to enter a title and whatever text you want. When you're satisfied with your post, click on the 'Submit' button at the bottom. If you're unsure of what sub-forum it belongs in, post it in General Discussion and a Mentor will move it to where it should be.
Go to the appropriate sub-forum (Classical Physics is this one). Just above the main body, there's a button that says 'New Thread'. Click on that, and you'll be prompted to enter a title and whatever text you want. When you're satisfied with your post, click on the 'Submit' button at the bottom. If you're unsure of what sub-forum it belongs in, post it in General Discussion and a Mentor will move it to where it should be.
- #7
Cundo007
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Thankss... i got a feeling ill be listening from you again...
- #8
Danger
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Don't let it become a habit; I make up half of the stuff that I post here.
- #9
yyouth24
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Ok, thank you very much.Danger said:Welcome to PF, Yyouth.
First off, thank you too much for driving me half nuts with your question. :grumpy: (
Anyhow, tungsten is a lot denser than iron, so internal particle collisions are far more numerous. Its other properties, though, are what make it so incredibly perfect for lightbulb use. To start with, it has one of the highest melting points of any metal. Combined with its very low thermal expansion coefficient, it allows bulbs to be run far hotter than could be achieved with other materials. That low expansion also allows a very long piece of wire to be put into a very small space. Filaments are typically double-coiled, wherein the original coiled wire is coiled again. The easiest way that I can think of to clarify that is if you were to take a long spring such as from a ball-point pen and wrap it around a toothpick. That 1/4" long filament would probably be over a metre long if stretched out. Tungsten is also very unreactive, so impurities that might sneak into the argon atmosphere of a bulb are less likely to cause failure.
- #10
yyouth24
- 16
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And when the element will be turned into liquid? Should the atoms be totally disintegrated?
Last edited:
1. Why does passing current heat wolfram filament in light bulb?
The wolfram (or tungsten) filament in a light bulb is heated by the passage of electrical current in order to produce light. As the current flows through the filament, it encounters resistance, which causes the filament to heat up and glow. This is known as the Joule effect, or resistive heating.
2. How does the heat from the current create light in a light bulb?
The heat generated by the current in the wolfram filament causes it to emit electromagnetic radiation, including visible light. This is known as incandescence, and it is the process by which traditional incandescent light bulbs produce light.
3. Why is wolfram used for the filament in light bulbs?
Wolfram (tungsten) is used for the filament in light bulbs because it has a high melting point and is a good conductor of electricity. This allows it to withstand the high temperatures and electrical currents needed to produce light in a light bulb.
4. How does the current affect the lifespan of a light bulb?
The current passing through the wolfram filament in a light bulb causes it to gradually wear down and thin out over time. This is known as "filament evaporation" and it is the main reason why incandescent light bulbs eventually burn out. The higher the current, the faster the filament will wear out and the shorter the lifespan of the light bulb will be.
5. Can passing too much current through the wolfram filament cause a light bulb to break or explode?
Yes, passing too much current through the wolfram filament can cause it to overheat and potentially break or explode. This is why it is important to use the correct wattage of light bulb for a given light fixture, as well as to handle and install light bulbs carefully to avoid damaging the filament.
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