Question

How does radiation differ from convection?
1.Radiation can move through empty space to transfer heat; convection cannot.
2.Radiation needs a medium in order for heat to transfer; convection does not.
3.Radiation requires objects to have direct physical contact; convection does not.
4.Radiation transmits heat by circulating particles in an object; convection does not.

Answer 1

Radiation differs from convection as follows: 1. Radiation can move through empty space to transfer heat; convection cannot.

• Radiation and convection, both are methods of heat transfer.
• Convection is a method of heat transfer in which heat is transferred with the help of the movement of the particles of the fluid. Thus, the convection method is applicable to liquids and gases.
• As convection includes the motion of particles of the medium, the medium is necessary for heat transfer through convection.
• While radiation is the method of heat transfer in which heat is transferred in the form of photons or electromagnetic waves.
• As electromagnetic waves can travel even in a vacuum, radiation can move through empty space to transfer heat.

Answer 2

1. Radiation can move through empty space to transfer heat; convection cannot.

Explanation:

Heat is an energy which is neither created nor destroyed. Heat is transferred from an object or material of higher temperature to an object or material of lower temperature.

Radiation and convection are two different modes of heat transfer.

Convection:  

• Convection is the heat transfer from the surface by means of fluid.
• Fluids undergo macroscopic movement for this mode of heat transfer.
• Natural convection can be explained as air is heated, it expands then rises and then is replaced by cool air. Example: in weather systems.
• IT REQUIRES MEDIUM.

Radiation:

• Radiation is the heat through empty space.
• Radiation occurs when electromagnetic wave is emitted or absorbed.
• Electromagnetic waves need to medium to travel.
• Does not require medium to travel.
• Example: sun's warmth on earth.