Why does blowing on a candle extinguish the flame, but blowing on a burning coal makes it hotter?
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Avijuno
ANSWERS: 1
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The two modes of burning are slightly different. In the case of the candle, what is happening is that solid wax is being vapoirised by the heat of the candle, so that the wick is surrrounded by a cloud of vapourised wax. This wax is then burning in the air, and providing the heat to melt and then vapourise more wax to keep the cloud going. Your breath disrupts this cloud so that there is no longer a stream of vapour from the candle to the cloud, and of heat from the burning cloud back to the candle. Apart from the very tip of the wick which is b urning off because it is no longer cooled by rising wax, no part of the candle itself is very hot. In the case of the coal, it is solid carbon that is burning of. The whole body of the coal is red hot, so that it doesn't need to get heat from elsewhere to keep it burning. Instead, your breath provides extra oxygen. It already has heat and carbon - its burning is controlled b y the fact that it exhausts nearby oxygen quickly. Give it more oxygen and it burns faster.
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