physics

Q.1 Distinguish between conduction, convection and radiation.


Conduction
Conduction is a process in which transfer of heat takes place between objects by direct contact.

1. Material medium is essential for transmission of heat by conduction.
2. Transmitted heat warms the medium.
3. No detectable motion of the particles of the medium occurs in this process.
4. Heat is conducted through any medium, solid, liquid or gas. In general, metals are very good conductors of heat.
5. Heat is transmitted in any direction through straight or curved. paths.
6. It is a slow process.


Convection
Convection refers to the form of heat transfer in which energy transition occurs within the fluid.

1. Material medium is essential for transmission of heat by convection.
2. Transmitted heat warms the medium.
3. Particles of the medium themselves carry thermal energy from a hotter to a colder place.
4. Convention can take place in liquids and gases, but not in a solid.
5. Heat is transmitted only in the upward direction through straight or curved paths.
6. It is a slow process.



Radiation
Radiation alludes to the mechanism in which heat is transmitted without any physical contact between objects.

1. Transfer of heat by radiation does not require any material medium at all.
2. Radiant heat does not warm the intervening medium, if any. A body gets heated by absorbing the incident radiant heat.
3. In this process heat is transferred by electromagnetic waves.
4. Heat is transmitted by this process through diathermanous mediums and not through athermanous mediums.
5. Radiant heat travels in straights lines in any direction.
6. It is an extremely rapid process. Radiant heat travels with the velocity of light.