A candle flame has three main zones, they are
1. The outer zone – complete combustion of the fuel takes place and the colour of the flame is blue and is the hottest part of the flame. It is the non-luminous part of the flame.
2. The middle zone – partial combustions of the fuel takes place and the colour of the flame is yellow and is moderately hot part of the flame. It is the luminous part of the flame.
3. The inner zone – There are unburnt vapours of the fuel and the colour is black and is least hot part.
