CONDUCTION

Conduction is defined as the process of thermal energy transfer without any flow of the material medium.


This simply means that conduction is the flow of heat energy through a medium/body. However, different materials have a different range of conductivity. Metals are usually the best conductors, while wood is usually the worst.






A simple experiment can illustrate this concept. First, you will need a wedge of butter, metal sticks(4 preferably: one of them zinc, another aluminium, iron and lastly, copper) and a candle.

Next. you place the wedge of butter on one of the metal sticks and heat it using the lighted candle. Record the time taken for the butter to melt and fall off. Repeat the experiment with the other metal sticks, and you can see the varying degrees of conductivity certain materials have.

Also, from this experiment, 2 other conclusions can be drawn:
firstly, conduction does not involve the material itself flowing. Merely the butter melted, and it did not alter the metal stick.
it reiterates that different materials have different levels of conductivity, even if they are all metals.

The process of conduction has to do with the atoms and molecules that make up the solids. Metals and non-metals differ greatly when it comes to whether they are insulators or conductors because metals contain many free electrons. These free electrons move randomly between atoms or molecules. Non -metals however, do not have them.

For instance, if a wooden rod and a copper rod were taken and heated at only one end, the atoms or molecules vibrate rigorously. They collide with other particles and they vibrate as well. Hence, kinetic energy is produced from the vibrations from the hot end. They are then transferred to the neighbouring atoms or molecules.

This happens in both the copper and wooden rods. However, as there are free electrons in the copper rod another process takes place. This is known as free electron diffusion.


When the copper rod is heated, the electrons in the copper rod gain kinetic energy through the vibrations. They then diffuse or spread into the cooler (or un-heated) parts of the metal. They collide with cooler parts in the metal and the kinetic energy is transferred to the cooler parts of the metal.

Conduction in Liquids & Gases
Liquids and gases are also matter. As this is so, they can also be transferred. That is- conducted from a hotter body to a colder body. However, conduction in liquids and gases is not as fast as conduction in solids. This is so as the atoms in solids are much closer together.

Application for Conduction

in the application of conduction, good and bad heat conductors are used. Cooking utensils- woks, kettles and saucepans are usually made up of metal to conduct heat and cook food faster.

Bad heat conductors are used for cooking utensil handles. This is to make sure that you do not get burnt when holding the utensils. As tabletops are usually glass, tablemats are made up of insulators to prevent damage. Also, woolen clothes can be used as examples of conduction. They are used to prevent coldness from reaching a body.