CBSE Class 11-science Answered

conduction:- It is a process of transfer of heat which takes place only in solids. Heat can be passed through conductors eg. all metals

Conduction of heat is the process of transfer of heat in solids by molecular vibration. Heat is transferred from the hotter part of a solid to colder parts by this process.

For example, if you heat one end of a metal spoon by holding the other end with your hand, you will observe that after a minute or so the temperature of the end you are holding has risen. Here, heat energy is transferred from the heated end to the end you are holding. This process of transfer of heat is called conduction.

convection:- It is a process of transfer of heat which takes place in liquids and gasses.

Convection is heat transfer by mass motion of a fluid (liquid and gas) such as air or water when the heated fluid is caused to move away from the source of heat, carrying energy with it. So, for convection to take place the molecules of the substance must be mobile. Only molecules of liquids and gases can move, hence, convection is possible in fluids (liquids and gases) only.

Radiation:- Radiation is a process in which no medium is used for heat transfer. Eg.radiation transfered from sun to earth. As we know that there is nothing between sun and earth exept vacuum so no medium is required for heat transfer for radiation