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Resolving to minmaj7
When a candle burns, why does the top of wick glow if bottom of flame is hottest?
Announcing the arrival of Valued Associate #679: Cesar Manara
Planned maintenance scheduled April 17/18, 2019 at 00:00UTC (8:00pm US/Eastern)Entropy and enthalpy change on mixing liquidsChemical equilibrium for simultaneous dissociation reactionsDoes the potential energy increase when temperature is raised?Spectrometry in Chemistry & Flame Test LabWhy does lead nitrate powder on heating starts turning yellow from the top rather than from the bottom?Is the flame temperature of a burning fuel affected by pre-heating the fuel?Why might copper have a lower heat capacity than lithium according to the Shomate Equation?Colored Flames ExperimentWhy does Magnesium burn hotter than other Group II metals?AP Chem Question about Reaction Rate - Confused?
$begingroup$
Totally an elementary question.
Staring at a candle, it appears that the bottom of the wick is dark whereas the top glows. However the bottom of the flame (the blue) is the hottest.
Is the reason for this that the concentration of liquid wax is greater at the bottom, offsetting the greater temperature at the bottom?
thermodynamics heat combustion light
New contributor
$endgroup$
add a comment |
$begingroup$
Totally an elementary question.
Staring at a candle, it appears that the bottom of the wick is dark whereas the top glows. However the bottom of the flame (the blue) is the hottest.
Is the reason for this that the concentration of liquid wax is greater at the bottom, offsetting the greater temperature at the bottom?
thermodynamics heat combustion light
New contributor
$endgroup$
$begingroup$
The yellow part of a flame is coloured by glowing tar/char and wick particles.
$endgroup$
– Karl
56 mins ago
add a comment |
$begingroup$
Totally an elementary question.
Staring at a candle, it appears that the bottom of the wick is dark whereas the top glows. However the bottom of the flame (the blue) is the hottest.
Is the reason for this that the concentration of liquid wax is greater at the bottom, offsetting the greater temperature at the bottom?
thermodynamics heat combustion light
New contributor
$endgroup$
Totally an elementary question.
Staring at a candle, it appears that the bottom of the wick is dark whereas the top glows. However the bottom of the flame (the blue) is the hottest.
Is the reason for this that the concentration of liquid wax is greater at the bottom, offsetting the greater temperature at the bottom?
thermodynamics heat combustion light
thermodynamics heat combustion light
New contributor
New contributor
edited 26 mins ago
A.K.
10.2k62671
10.2k62671
New contributor
asked 1 hour ago
ZARZAR
1161
1161
New contributor
New contributor
$begingroup$
The yellow part of a flame is coloured by glowing tar/char and wick particles.
$endgroup$
– Karl
56 mins ago
add a comment |
$begingroup$
The yellow part of a flame is coloured by glowing tar/char and wick particles.
$endgroup$
– Karl
56 mins ago
$begingroup$
The yellow part of a flame is coloured by glowing tar/char and wick particles.
$endgroup$
– Karl
56 mins ago
$begingroup$
The yellow part of a flame is coloured by glowing tar/char and wick particles.
$endgroup$
– Karl
56 mins ago
add a comment |
2 Answers
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active
oldest
votes
$begingroup$
Because fire is not the same thing as light.
Michael Faraday did a wonderful job of explaining how the candle works, and I direct to look at it (there are also Youtubes videos giving a modern take on this work) if you're interested.
In short, the candle produces light, not because it is hot, but because it is sooty. The particles of soot glow when they are hot (blackbody radiation), and that's what produces light.
If you take a flame where the fuel is very well-mixed with oxygen and the flame that's produced is not sooty, it does not glow like a candle even though it's very hot. This is precisely why Bunsen burners are used in a laboratory. They give a hot but non-illuminating flame that's great for doing analysis.
$endgroup$
$begingroup$
I just browsed a bit in the Faraday lecture for children: wonderful!
$endgroup$
– Karsten Theis
2 mins ago
add a comment |
$begingroup$
The top of the wick glows because it is hotter than the bottom. The wick temperature does not have to be the same as the flame temperature.
For a candle, the wick burning isn't the intended purpose of the wick; light comes from burning wax (more generally: fuel), you want to burn the wax not the wick. Rather the purpose purpose of a wick is to help fuel evaporate by soaking up wax and allowing the radiant energy from the flame to heat the wax causing it to evaporate and burn also.
As wax travels up the wick, it evaporates and less wax is in the wick the further up you go. Eventually the dries up and the radiant energy is heating a wick without any wax. Eventually the wick get so hot at the tip, that it will glow due to black-body radiation.
In summary: though the blue is the hottest part of the flame, the wick can evaporate wax to cool towards the bottom. There is no wax at the top and thus as the radiant energy of the flame causes it to get hotter until it starts to glow.
Extra: I will note that the top of the wick does not burn when lit as the gas around the wick has too little oxygen to burn (unless the wick slumps out side the flame). When you blow out the candle the low oxygen environment of a flame is gone and thus the hot wick will smolder.
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2 Answers
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2 Answers
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$begingroup$
Because fire is not the same thing as light.
Michael Faraday did a wonderful job of explaining how the candle works, and I direct to look at it (there are also Youtubes videos giving a modern take on this work) if you're interested.
In short, the candle produces light, not because it is hot, but because it is sooty. The particles of soot glow when they are hot (blackbody radiation), and that's what produces light.
If you take a flame where the fuel is very well-mixed with oxygen and the flame that's produced is not sooty, it does not glow like a candle even though it's very hot. This is precisely why Bunsen burners are used in a laboratory. They give a hot but non-illuminating flame that's great for doing analysis.
$endgroup$
$begingroup$
I just browsed a bit in the Faraday lecture for children: wonderful!
$endgroup$
– Karsten Theis
2 mins ago
add a comment |
$begingroup$
Because fire is not the same thing as light.
Michael Faraday did a wonderful job of explaining how the candle works, and I direct to look at it (there are also Youtubes videos giving a modern take on this work) if you're interested.
In short, the candle produces light, not because it is hot, but because it is sooty. The particles of soot glow when they are hot (blackbody radiation), and that's what produces light.
If you take a flame where the fuel is very well-mixed with oxygen and the flame that's produced is not sooty, it does not glow like a candle even though it's very hot. This is precisely why Bunsen burners are used in a laboratory. They give a hot but non-illuminating flame that's great for doing analysis.
$endgroup$
$begingroup$
I just browsed a bit in the Faraday lecture for children: wonderful!
$endgroup$
– Karsten Theis
2 mins ago
add a comment |
$begingroup$
Because fire is not the same thing as light.
Michael Faraday did a wonderful job of explaining how the candle works, and I direct to look at it (there are also Youtubes videos giving a modern take on this work) if you're interested.
In short, the candle produces light, not because it is hot, but because it is sooty. The particles of soot glow when they are hot (blackbody radiation), and that's what produces light.
If you take a flame where the fuel is very well-mixed with oxygen and the flame that's produced is not sooty, it does not glow like a candle even though it's very hot. This is precisely why Bunsen burners are used in a laboratory. They give a hot but non-illuminating flame that's great for doing analysis.
$endgroup$
Because fire is not the same thing as light.
Michael Faraday did a wonderful job of explaining how the candle works, and I direct to look at it (there are also Youtubes videos giving a modern take on this work) if you're interested.
In short, the candle produces light, not because it is hot, but because it is sooty. The particles of soot glow when they are hot (blackbody radiation), and that's what produces light.
If you take a flame where the fuel is very well-mixed with oxygen and the flame that's produced is not sooty, it does not glow like a candle even though it's very hot. This is precisely why Bunsen burners are used in a laboratory. They give a hot but non-illuminating flame that's great for doing analysis.
answered 53 mins ago
ZheZhe
13.2k12650
13.2k12650
$begingroup$
I just browsed a bit in the Faraday lecture for children: wonderful!
$endgroup$
– Karsten Theis
2 mins ago
add a comment |
$begingroup$
I just browsed a bit in the Faraday lecture for children: wonderful!
$endgroup$
– Karsten Theis
2 mins ago
$begingroup$
I just browsed a bit in the Faraday lecture for children: wonderful!
$endgroup$
– Karsten Theis
2 mins ago
$begingroup$
I just browsed a bit in the Faraday lecture for children: wonderful!
$endgroup$
– Karsten Theis
2 mins ago
add a comment |
$begingroup$
The top of the wick glows because it is hotter than the bottom. The wick temperature does not have to be the same as the flame temperature.
For a candle, the wick burning isn't the intended purpose of the wick; light comes from burning wax (more generally: fuel), you want to burn the wax not the wick. Rather the purpose purpose of a wick is to help fuel evaporate by soaking up wax and allowing the radiant energy from the flame to heat the wax causing it to evaporate and burn also.
As wax travels up the wick, it evaporates and less wax is in the wick the further up you go. Eventually the dries up and the radiant energy is heating a wick without any wax. Eventually the wick get so hot at the tip, that it will glow due to black-body radiation.
In summary: though the blue is the hottest part of the flame, the wick can evaporate wax to cool towards the bottom. There is no wax at the top and thus as the radiant energy of the flame causes it to get hotter until it starts to glow.
Extra: I will note that the top of the wick does not burn when lit as the gas around the wick has too little oxygen to burn (unless the wick slumps out side the flame). When you blow out the candle the low oxygen environment of a flame is gone and thus the hot wick will smolder.
$endgroup$
add a comment |
$begingroup$
The top of the wick glows because it is hotter than the bottom. The wick temperature does not have to be the same as the flame temperature.
For a candle, the wick burning isn't the intended purpose of the wick; light comes from burning wax (more generally: fuel), you want to burn the wax not the wick. Rather the purpose purpose of a wick is to help fuel evaporate by soaking up wax and allowing the radiant energy from the flame to heat the wax causing it to evaporate and burn also.
As wax travels up the wick, it evaporates and less wax is in the wick the further up you go. Eventually the dries up and the radiant energy is heating a wick without any wax. Eventually the wick get so hot at the tip, that it will glow due to black-body radiation.
In summary: though the blue is the hottest part of the flame, the wick can evaporate wax to cool towards the bottom. There is no wax at the top and thus as the radiant energy of the flame causes it to get hotter until it starts to glow.
Extra: I will note that the top of the wick does not burn when lit as the gas around the wick has too little oxygen to burn (unless the wick slumps out side the flame). When you blow out the candle the low oxygen environment of a flame is gone and thus the hot wick will smolder.
$endgroup$
add a comment |
$begingroup$
The top of the wick glows because it is hotter than the bottom. The wick temperature does not have to be the same as the flame temperature.
For a candle, the wick burning isn't the intended purpose of the wick; light comes from burning wax (more generally: fuel), you want to burn the wax not the wick. Rather the purpose purpose of a wick is to help fuel evaporate by soaking up wax and allowing the radiant energy from the flame to heat the wax causing it to evaporate and burn also.
As wax travels up the wick, it evaporates and less wax is in the wick the further up you go. Eventually the dries up and the radiant energy is heating a wick without any wax. Eventually the wick get so hot at the tip, that it will glow due to black-body radiation.
In summary: though the blue is the hottest part of the flame, the wick can evaporate wax to cool towards the bottom. There is no wax at the top and thus as the radiant energy of the flame causes it to get hotter until it starts to glow.
Extra: I will note that the top of the wick does not burn when lit as the gas around the wick has too little oxygen to burn (unless the wick slumps out side the flame). When you blow out the candle the low oxygen environment of a flame is gone and thus the hot wick will smolder.
$endgroup$
The top of the wick glows because it is hotter than the bottom. The wick temperature does not have to be the same as the flame temperature.
For a candle, the wick burning isn't the intended purpose of the wick; light comes from burning wax (more generally: fuel), you want to burn the wax not the wick. Rather the purpose purpose of a wick is to help fuel evaporate by soaking up wax and allowing the radiant energy from the flame to heat the wax causing it to evaporate and burn also.
As wax travels up the wick, it evaporates and less wax is in the wick the further up you go. Eventually the dries up and the radiant energy is heating a wick without any wax. Eventually the wick get so hot at the tip, that it will glow due to black-body radiation.
In summary: though the blue is the hottest part of the flame, the wick can evaporate wax to cool towards the bottom. There is no wax at the top and thus as the radiant energy of the flame causes it to get hotter until it starts to glow.
Extra: I will note that the top of the wick does not burn when lit as the gas around the wick has too little oxygen to burn (unless the wick slumps out side the flame). When you blow out the candle the low oxygen environment of a flame is gone and thus the hot wick will smolder.
answered 24 mins ago
A.K.A.K.
10.2k62671
10.2k62671
add a comment |
add a comment |
ZAR is a new contributor. Be nice, and check out our Code of Conduct.
ZAR is a new contributor. Be nice, and check out our Code of Conduct.
ZAR is a new contributor. Be nice, and check out our Code of Conduct.
ZAR is a new contributor. Be nice, and check out our Code of Conduct.
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$begingroup$
The yellow part of a flame is coloured by glowing tar/char and wick particles.
$endgroup$
– Karl
56 mins ago