Flame - I
Combustion is a process in which a substance reacts with oxygen to give off heat and light.
This light may be in the form of flame or glow.
For examples, candles which burn with a flame;
While coal burns with a glow.
Substances that vapourise upon burning produce a flame
For example, combustion of kerosene oil produces flame
Now, let us look at the flame of the candle
From far it looks yellowish and luminous.
But if you observe the flame closely we observe three different colours of the flame
So, the flame is divided into three zones based on its colours.
And the first zone that we are going to talk about is the outermost part of the flame
This outer zone is blue in colour.
Here, complete combustion happens because of the presence of good amount of oxygen
And it is the hottest zone as more heat is produced due to the complete combustion that takes place in this region.
This zone is also called the non-luminous zone of the flame
The second zone is the middle luminous zone
The middle zone is yellow in colour
This zone is less hotter than the outermost zone
This is because there is a limited supply of of oxygen and hence only partial combustion takes place.
This partial combustion makes this region burn with an orange colour and is thus luminous.
The last zone is the innermost zone
This part is closes to the wick.
Due to lack of oxygen, proper combustion does not take place,
Hence the innermost zone has unburnt particles of carbon from the wick;
And presence of black unburnt carbon particles give this zone the name: Dark zone.
And this zone is the least hot of all the other zones in the flame.
Substance that vapourise while burning produces the flame
For example, combustion of kerosine oil produces flame
If you observe the flame closely we observe three different colours of the flame
In the outermost part of the flame, complete combustion happens because of lot of oxygen
Whereas due to less oxygen, partial combustion takes place in the middlemost zone
And lastly the innermost zone has unburnt wax because of lack of oxygen