Thermal Conductivity and its coefficient

Trying to cross the street barefooted in the summer results in the burning of feet.

Since the heat is being conducted from the asphalt to our feet.

Conduction is the process of heat transfer in the solids.

The conduction process occurs due to the free electron transfer and molecular vibration.

The material which allows the heat to pass through it called the conductors and the ability of the material to conduct heat through it called the conductivity.

The thermal conductivity of a material is defined by its coefficient and it is represented by the symbol .

Let's understand the coefficient of conduction.

Consider a rod of length and cross-sectional area .

Suppose there are two sinks and of the infinite thermal capacity. The temperature of the sinks are and . respectively, and > .

The rod is connecting two sinks.

The heat flows from a higher temperature to the lower temperature i.e. from sink to through the rod.

It is assumed that there is no heat transfer in the transverse direction. The heat flows in the longitudinal direction only.

Therefore, it is the case of heat flow.

Here, the rate of heat transfer through the conduction will depend on the temperature difference between the sinks, the area of the cross-section of the rod and the length of the rod.

The rate of heat transfer is directly proportional to the difference of temperature of between the sink and .

The rate of heat transfer is directly proportional to the area of the cross-section of the rod or the area normal to the direction of heat transfer.

And it is inversely proportional to the length of the rod.

If all the proportionality equations of heat transfer are combined, the rate of heat transfer can be written as,

To remove the proportionality, we have to introduce the proportionality constant in the equation of heat transfer.

is the thermal conductivity of the material of the rod and it differs from material to material.

The unit of thermal conductivity is .

Revision

The material which allows the heat to pass through it called the conductors.

The ability of the material to conduct heat through it called the conductivity.

is the thermal conductivity of the material of the rod and it differs from material to material.

The end