Staedy Conduction Heat Transfer - Practice Questions & MCQ

In the previous concept, we have learned the definition of Conduction. Now we will discuss the characteristics and properties of conduction - 

(1) Heat flows from high temperature to low temperature. In this, the particles of the medium simply vibrate about their mean position but do not leave their place.
(2) Conduction heat transfer is medium dependent.
(3) The temperature of the medium goes on increasing in the direction of heat transfer.
(4) Conduction mode of heat transfer is the process that is possible in all states of matter.
(5) In solids, the only mode of heat transfer is conduction.    

(6) In metallic solids, free electrons carry is the heat energy carrier, therefore they are good conductors of heat.

Terminologies used in steady state or basics of conduction - 

Steady-state: It means that the temperature in the system is not time-dependent. So, if we supply heat to a body then the temperature of the body increases but after some time, a state is reached when the temperature of every cross-section of the body becomes constant. In this state, no heat is absorbed by the body. This state of the body is called a steady state.

Isothermal surface : Any cross-section (within a conductor) having its all points at the same temperature, is called isothermal surface. 

Temperature gradient : The rate of change of temperature with distance between two isothermal surfaces is called temperature gradient. It is denoted by - 
So, 

Temperature gradient $=\frac{-\Delta \theta}{\Delta x}$
The negative sign show that temperature $\theta$ decreases as the distance $x$ increases in the direction of heat flow.

Thermal conductivity(K) - It is the measure of the ability of a substance to conduct heat through it. The magnitude of K depends only on nature of the material. Substances which do not permit easy flow of heat are called bad conductors. They possess low thermal conductivity due to very few free
electrons.