Question

In which of the following processes of heat transfer no medium is required?

• A. Conduction
• B. Convection
• C. Radiation
• D. All

Answer 1

Answer:

C. Radiation

Conduction:

• Heat conduction is the process in which heat is transferred from the hotter part to the colder part in a body without involving any actual movement of the molecules of the body.

• Heat transfer takes place from one molecule to another molecule as a result of the vibratory motion of the molecules.

• Heat transfer through the process of conduction occurs in substances which are in direct contact with each other.

• It generally takes place in solids.

Convection:

• Convection is the movement of molecules of a liquid or gas within itself.

• Here heat is transferred in the liquid and gases from a region of higher temperature to a region of lower temperature.

• Convection heat transfer occurs partly due to the actual movement of molecules or due to the mass transfer.

Radiation:

• Thermal radiation is the loss of heat from a solid object into the atmosphere via the release of electromagnetic radiation.

• Thermal radiation occurs as a result of random motion of molecules in matter.

• Hence heat transfer through radiation does not require a medium.