Explain what is meant by coefficient of linear thermal expansion.?

Answer 1

From Wikipedia:

During heat transfer, the energy that is stored in the intermolecular bonds between atoms changes. When the stored energy increases, so does the length of the molecular bond. As a result, solids typically* expand in response to heating and contract on cooling; this response to temperature change is expressed as its coefficient of thermal expansion:

The coefficient of thermal expansion is used in two ways:

* as a volumetric thermal expansion coefficient
* as a linear thermal expansion coefficient

These characteristics are closely related. The volumetric thermal expansion coefficient can be measured for all substances of condensed matter (liquids and solid state). The linear thermal expansion can only be measured in the solid state and is common in engineering applications.

* Some substances have a negative expansion coefficient, and will expand when cooled (e.g. freezing water).

Answer 2

Linear thermal expansion is a property of some materials. Put simply, it means when heated (get it? thermal implies heat) the material expands, typically measured in the longest dimension (linear or along a line). For example, a length of steel, say 30 feet long, may when heated, say from 60 degrees to 160 degrees, lengthen about an inch. The coefficient helps tell us how much the steel will lengthen given a stated temperature rise. But, for all the reasons so will explained in the previous answer the steel will only shrink so much, when cooled. It is a very useful value to know when designing structures such as bridges. The designer has to take into account the expansion and contraction of the steel bridge. This is often done using "expansion joints" which allow the bridge to expand without causing any damage.