Question

The fastest mode of transfer of heat is through:
A.) Convection
B.) Conduction
C.) Radiation
D.) All of the above

Answer 1

Hint: For this kind of question we need to understand what type of transfer methods are possible for heat transfer and how it is being executed.

Complete step by step answer:

We know that heat is a form of energy and it can be transferred using any of the three methods like conduction, convection and radiation.

Conduction: Heat is transferred across two bodies or in an extended body whose one end is heated. The molecules in the hotter section of the body will have more kinetic energy so they collide with molecules in the colder part of the body which leads to the transfer of energy through collision. The rate of conduction depends on many factors, the temperature gradient of the body, the length, area of cross section and physical properties of material.

Convection: It usually happens in fluids, when the fluid is heated, the molecules near the source of heat are heated first and become expanded and less dense than the molecules above, so the less dense molecules move up and dense molecules above move down till heat is uniformly transferred across the liquid.

Radiation: Thermal radiation generated from electromagnetic waves. Radiation occurs through vacuum or any other material medium. The heat is transferred at the speed of the electromagnetic wave in the medium, which is the speed of light in the medium. So radiation is the fastest among the three due to this reason.

So the answer to the question is option (C)- Radiation.

Note: The sun is a clear example of heat radiation that transfers heat across the solar system.
At normal room temperatures, objects radiate as infrared waves.
The temperature of the object affects the wavelength and frequency of the radiated waves. As temperature increases, the wavelengths within the spectra of the emitted radiation decrease and emit shorter wavelengths with higher-frequency radiation.