Question

Which one of the following is/are the fastest mode(s) of heat transfer?

• A. Convection
• B. Conduction
• C. Both conduction and convection
  
• D. Radiation

Answer 1

The correct option is D Radiation

Conduction takes place through vibration of particles around their mean positions.
Also, convection takes place through actual movement of particles from one place to another in the medium.
Radiation of heat is just like propagation of light and it takes place at the speed of light.
As radiation does not require any kind of movement or vibration of particles and it takes place directly without the aid of medium, it is the fastest mode of heat transfer.