Lap report on the measurement of coefficient of linear expansion for steel, copper, and aluminum.
Introduction
Generally, solid expands when heated. The increase in heat increases the vibration of atoms in the solid which brings about the increase in the separation of these atoms in the solid. For instance, if a solid of length L is subjected to a reasonably small temperature change of ∆T, it brings a change in the length of ∆L. The ∆L is directly proportional to ∆T and L.
Mathematically: ∆L=αL∆T, where α is the coefficient of linear expansion for the material.
Non-isotropic material has varying values of α which relies much on the axis along which the expansion is taken. This experiment measures the coefficient of linear expansion for (α) for aluminum, steel, and copper. These metals are isotropic hence required to be taken along one dimension. The equation ∆L=αL∆T applies well as long as α does not change over temperature change. If the α changes, the equation has to be integrated.
Procedures
The length L of a copper tube is measured at room temperature. Both the inner edge and the inner bracket of the stainless steel pin is measured and recorded in table 1. Copper tube is mounted in the expansion base as shown below.