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Name: Ralph F. O.
Status: other
Age: 60s
Location: N/A
Country: N/A
Date: Saturday, May 25, 2002


Question:
Why does a candle flame go out when you place a piece of coiled copper wire around it? i.e., a piece of copper wire is wrapped around a pencil to form a loose series of coils (5-6). It is held by the straight piece that was not coiled, and the coiled portion is placed around a candle flame so the flame is in the center. The flame appears to go out but relights when the coil is removed.


Replies:
Ralph,

The copper coil cools the gas envelope of the flame to the point where it is no longer hot enough to enable combustion. I suspect that if you hold the coil in the flame zone for a while after the flame goes out it would not re-ignite because the combustion environs would cool below the ignition point of the gases.

Regards,
ProfHoff 433


Combustion requires three things: fuel (wax here), oxygen (air here), ignition temperature (a match here probably). Remove one and the combustion stops -- that's the principles firemen use to put out fires. In the case of your candle the high thermal conductivity of copper probably is conducting sufficient heat from the flame that the flame goes out, but the heat capacity of the melted wax, wick, etc. probably "holds" enough heat that the temperature exceeds the ignition temperature if the copper wire is removed. If this mechanism is operating you can test it by holding the copper coil around the flame area for some time, so that the molten wax and wick cool, the flame will not re-ignite when you remove the copper coil.

Vince Calder



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