Question

Name the process of heat transfer in a solid.
A. Conduction
B. Convection
C. Radiation
D. Both A and B

Answer 1

Hint:Before we understand the kind of heat transfer that takes place in a solid, it is important to understand the structure of solids. The solid consists of molecules packed closely and the intermolecular force of attraction in solids is very higher than liquid or a gas.

Complete step-by-step answer:
The subject of heat transfer is a sub-discipline of thermal sciences. The sub-branch thermodynamics deals with the interaction of heat and work with the system and surroundings, but however, it does not indicate the way or the method in which the heat is transferred across the system and surroundings. In thermodynamics, only the total amount of heat transferred can be calculated but, not the method in which heat is transferred.
The sub-discipline of heat transfer specifically, deals with the phenomenon involving the exchange of heat between the system and the surroundings.
There are three major forms of heat transfer namely, A. Conduction B. Convection C. Radiation
In conduction, there is no real movement of the particles of the medium. The particles of the medium vibrate about its mean position thereby, transferring the heat energy to the adjacent molecules.
In convection, there is actual movement of the particles of the medium. The particles of the medium get heated and travel away from the system, thereby taking heat away and they deposit the heat in other places by cooling.
In radiation, there is no involvement of the medium in between. The heat energy is directly transferred in the form of electromagnetic radiation.

As per the definitions of these three modes of heat transfer, conduction requires the medium to be elastic since the particles have to return to their original form and state after it has passed the heat to the next medium. This elasticity is only observed in solids than in fluids. Hence, conduction occurs in solids.
As there is no requirement of a medium in radiation, it can happen in solids as well as in fluids.
Therefore, the heat transfer in a solid happens through conduction as well as radiation.

Hence, the correct option is Option D.

Note:In this answer, the elasticity refers to the property of a solid known as stiffness, which is indicated by the ratio called Young’s Modulus. Fluids do not possess young’s modulus but another modulus of elasticity called Bulk modulus is applicable to them, which supports the convection phenomenon.