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We Know Now That Heat From A Candle Will Be Transferred To The Air Around It. These Will Warm Up. Where Will This Air Move To?

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#1 nstar348

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Posted 23 December 2016 - 06:49 AM

I am a student and need help answering this question. I am aware as to what convection, conduction and radiation means.


We know now that heat from a candle will be transferred to the air around it. These will warm up. Where will this air move to?

Thank you and help would be appreciated

#2 exchemist

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Posted 23 December 2016 - 06:55 AM

I am a student and need help answering this question. I am aware as to what convection, conduction and radiation means.


We know now that heat from a candle will be transferred to the air around it. These will warm up. Where will this air move to?

Thank you and help would be appreciated

This air will expand as a result of heating, which will make it less dense than the surrounding air and thus more buoyant. So it will rise. This will create a convection current in the air. Eventually the warmer air will mix with the surrounding air and give up its heat to it.  


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#3 nstar348

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Posted 23 December 2016 - 07:01 AM

I am also struggling on another question:

how is energy transferred to your hand when you feel the warmth on the side of the candle?

KindRegards

#4 exchemist

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Posted 23 December 2016 - 07:25 AM

I am also struggling on another question:

how is energy transferred to your hand when you feel the warmth on the side of the candle?

KindRegards

Two ways:

 

1) There will be radiation (visible and IR) from the flame that is absorbed by the the molecules in the skin of your hand. As a result these molecules gain energy which will make them move faster - which is an increase in the temperature.

 

2) Hot air from the candle will give up its heat to your hand, especially if your hand is above the flame.  This is why you burn your hand so much more easily if you hold it above the candle flame than if you hold it beside the flame.


Edited by exchemist, 23 December 2016 - 07:25 AM.


#5 OceanBreeze

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Posted 23 December 2016 - 08:13 AM

convectionflame.jpg


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