Question

Which method(s) of energy transfer does not require matter? Which method(s) of energy transfer does require matter? Give an example of each

Answer 1

Part ( a)

Radiation is a mode of Heat transfer that does not require any kind of involvement of matter . It travels even in vacuum .

For example : light and heat from sun reaches to earth through radiation mode of Heat transfer.

Part (b)

Conduction and convection are methods of Heat transfer that require matter for the transfer of Heat.

The only difference between conduction and convection method of Heat transfer is that :

1) In conduction , Heat transfer takes place by the collision and vibration of molecules and atoms at their mean position.

2) whereas in convection Heat transfer takes place due to actual transfer of matter which mostly occurs in liquids and gases.

Example of conduction : when you Heat a metal rod at one end , the other end of rod gets heated because of conduction mode of Heat transfer

Example of convection : when you place a cold water container in a burning stove , bottom-most part of water gets heated and it starts rising up and denser water comes down . Hence exchange of Heat takes place because of actual transfer of matters.