Applications of Thermal Conductivity


Examples of conductors and insulators

Examples of conductors are metals(silver, copper and aluminium, etc), mercury, earth, etc.
Examples of insulators are non-metals (plastic, glass, pure water, sulphur, etc). Some exceptions that are non-metals but not insulators are graphite and tap water.


Uses of good conductors

The following are some uses of good conductors of heat
  1. Cooking utensils are made from good conductors of heat such as copper, brass, steel, aluminium etc.,as the  utensils get heated up quickly and food can be cooked efficiently in shorter time. 
  2. Mercury is used in a thermometer as it is a very good conductor of heat such that it acquires the temperature to be measured by the thermometer.
  3. Copper being a good conductor of heat is used in electric geyser, to conducts heat from the heated element to the water in the geyser.
  4. The bit of a soldering iron is made of copper. As the tip of the hot bit comes into contact with the material  to be soldered, heat is rapidly conducted from its heated parts to its tip. So the temperature of the tip becomes more than the melting point of the soldering material and the soldering material  gets melted soon.


Good and Bad conductors of heat

Most metals are good conductors of heat; silver and copper are exceptionally good. On the other hand, substances such as cork, wood, cotton and wool are bad conductors. Both good and bad conductors have their uses. The bit of a soldering iron is made of copper, so that when its tip is cooled through contact with the work, heat is rapidly conducted from the body of the bit to restore the temperature of the tip and maintain it above the melting-point of solder.
Bad conductors have a very wide application. Beginning with our own personal comfort, we prevent loss of heat from ourselves by covering of poorly conducting material. Textiles are bad conductors of heat, since they are full of tiny pockets of air enclosed by the fibres of the material. Air, in common with all gases, is a very bad conductor of heat. It is usual to say that wool is warmer than cotton. Technically, of course, we imply that it has a lower thermal conductivity than cotton. Double glazing in windows reduces heat loss from a building owing to the poorly conducting layer of air between the two sheets of glass.