Question 1 How many zones are there in a flame?
Question 2 Which zone of candle is the hottest?
Question 3 Which zone of candle is the coldest?
Question 4 What is the colour of inner most flame?
Question 5 What is the colour of outer most flame?
Question 6 Name the various zones of candle flame?
Question 7 In which zone partial combustion of fuel take place?
Question 8 In which zone complete combustion of fuel take place?
Question 9 Make a labelled diagram of a candle flame?
Question 10 What makes the middle zone of a candle flame luminous?
Question 11 Why does a goldsmith blow air into kerosene lamp flame with a blow-pipe?
Structure of flame
A flame consist of three zones.These are Innermost zone,middle zone,outer zone.The three zones of a flame have different colours and different temperature.
1) The Innermost zone of a flame is dark or black:It consist of hot,unburnt vapours of the combustible material.It is the least hot part of the flame.It is the coldest part of the flame.
2)The middle zone of a flame is yellow:It is bright and luminous.The fuel vapours burn partially in the middle zone because there is not enough air of burning in this zone.The partial burning of fuel in the middle zone produces carbon particles.These carbon particles then leave the flame as smoke and soot.It has moderate temperature.
3)The outer zone of a flame is blue:It is a non-luminous zone.In this zone,complete combustion of the fuel takes place because there is plenty of air around it.The outermost zone has the highest temperature in the flame.It is the hottest part of the flame.It is quite thin as compared to middle zone.
Goldsmith blow air with a blow-pipe to intensify a kerosene lamp flame for melting and moulding pieces of gold and silver into desired shapes to make jewellery.When air is blown through blow-pipe into the flame,it helps in the combustion of unburnt fuel and hence make the flame hotter.