Question

Convection occurs in
(A) Solids only
(B) Liquids only
(C) Gases only
(D) Fluids

Answer 1

Hint: To answer this question, we need to look into the basic definition of Convection. It is the phenomenon that causes the transfer of heat within matter. Then we have to find the required condition for this phenomenon to take place.

Complete step by step answer
Convection is one of the phenomena which are responsible for the heat transfer within the matter. We know that there are three different modes of transfer of heat within the matter. These are conduction, convection, and radiation.

While the conduction is carried out as a result of the temperature difference between the two adjacent points in a matter, the radiation is carried by the electromagnetic waves. In both of these phenomena, there is no need for the matter itself to be moved for transferring the heat. But the convection is a phenomenon in which actual movement of the matter is involved. The part of the matter which is directly heated becomes light, and rises up and takes the place of the colder part of the matter. Then the colder part becomes heated and this cycle goes on. This way the heat transfer within the matter takes place.

So convection can occur only in the matter which is capable of showing motion. We know that the solids cannot show any kind of motion. So convection cannot occur in solids.
So the option A is incorrect.
But as we know, the liquids and the gases, collectively known as the fluids, have the capability of flowing. So convection can take place in fluids.

Hence, the correct answer is option D.

Note
The process of convection, which has been discussed in this question, is responsible for many day to day phenomena. For example, the land is warmer than water during the day, but the opposite is true during the night.