Heat Transfer Through Conduction


 
 
Concept Explanation
 

Heat Transfer Through Conduction

Transfer of heat:

Heat is transferred by conduction, convection and radiation.

Conduction -

Transfer of heat from one particle to the adjacent particle is known as conduction of heat. In solids, heat is transferred by the process of conduction. In this process, the transfer of heat takes place through adjacent molecules.

Example: When one end of an iron rod is put over flame then part which is nearer to the flame is heated first and heat is gradually transferred to the other end of the rod. This happens because particles of iron rod which are nearer to the flame receive the heat and transfers this to the adjacent particles. Subsequently, the adjacent particles transfer the heat to the next adjacent particles. This process continues and heat reaches to the other end of the rod. Thus, heat transfer in solid takes place through conduction.

Conductor and Insulator:

Materials which allow heat to pass through it are called conductor or good conductor of heat, such as iron, copper, aluminium, etc. All metals are good conductors of heat. Since, mercury is a metal and found in liquid state at room temperature, that’s why it is used in thermometer.

Since metals are the good conductor of heat that’s why kitchen utensils are made of metals or alloys of metals.

Materials which do not allow heat to pass through them are called bad conductor or poor conductor of heat. They are also called insulators. Example: rubber, wood, plastic, etc. This is the cause that handles of frying pan or other kitchen utensils are made of plastic.

Application Of Conduction And Insulators

  • Cooking utensils are made of good conductors of heat. Such utensils get heated quickly. Food can be cooked efficiently in a shorter time. Hence the utensils are generally made of copper, brass, steel or aluminum.
  • The base of an electric iron conducts heat which in turn helps in ironing the clothes effectively. Had the base been made of an insulator, the clothes wouldn’t have got ironed de to lack of conduction of heat.
  • The handles of kettles and utensils are made of insulators such as wood, plastic or ebonite. They help us in holding the utensils comfortably as they do not get heated.
  • Woolen clothes are bad conductors. They do not allow heat to transfer from our body to the external environment and thus keep us warm.
  • Building materials like brick, asbestos, mud and grass are insulators of heat. They do not permit heat or cold to pass through the walls of the bricks. They keep the houses warm in winters and cool in summers. Roof sheds are made of asbestos for the same reason.
  • Hair and the fur of animals are bad conductors of heat. They protect them from cold.
  • Vehicles carrying inflammable materials such as petrol are covered or coated with insulators. Otherwise, the petrol can get heated up and catch fire.
  • Sample Questions
    (More Questions for each concept available in Login)
    Question : 1

    Stainless steel pans are usually provied with copper bottoms. The reason for this could be that

    Right Option : C
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    Explanation
    Question : 2

    Which of the following are correct ?

    (a) In solids, heat is transferred by the process of conduction.

    (b) The materials which allow heat to pass through it are called conductor

    (c) The handles of kettles and utensils are made of insulators such as wood, plastic .

    Right Option : D
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    Explanation
    Question : 3

    A wooden spoon is dipped in a cup of icecream , then its other end _______________

    Right Option : D
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    Explanation
     
     


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