Law Of Thermal Conductivity MCQ - Practice Questions with Answers

Law of Thermal Conductivity - 

Consider a rod of length 'l' , area of cross-section 'A' whose faces are maintained at temperature and respectively. In steady state the amount of heat flowing from one face to the other face in time t is given by - 

So, from the above equation we can calculate the -  Rate of flow of heat i.e. heat current which can be written as - 

In the differential form, this heat current can also be written as - 

In case of non-steady state or variable cross-section, this is the more general equation can be used to solve problems.

Relation of thermal conductivity of some material - 

Thermal resistance (R_th) : The thermal resistance of a body is defined as the measure of its opposition to the flow of heat through it. It is defined as the ratio of temperature difference to the heat current.