What are the main conditions necessary …

Transfer of heat: To carry heat from one part of an object to its other part or from one object to another object is called transfer of heat. Like if we dip a steel spoon in a cup of hot tea, we find that the temperature of a spoon rises and it becomes hot. The heat transfers from an object at higher temperature to another object at lower temperature. The transfer of heat stops when the two objects attain same temperature. The heat can be transferred from a hot to cold object in three different ways:

a. By conduction: The process by which heat is transferred from the hotter end to the colder end of an object is known as conduction. The conduction process takes place only in solids.

b. By convection: The process by which heat is transferred from the hotter parts of a liquid to its colder parts by the movement of the liquid itself is known as convection. For e.g. water is a good convector.

c. By radiation: The process of transfer of heat of hot electric bulbs to our hand held below it is called radiation.