Identify the material having the lowest coefficient of linear expansion.

Concept:

Thermal Expansion:

• Thermal expansion is the phenomenon observed in solids, liquids, and gases. In this process, an object or body expands on the application of heat (temperature).
• It defines the tendency of an object to change its dimension either in length, density, area, or volume due to heat. When the substance is heated it increases its kinetic energy.
• Thermal expansion is of three types: Linear expansion, Area expansion, Volume expansion

Linear Expansion:

• Linear expansion is the change in length due to heat.
• The linear expansion formula is given as, \(\frac{Δ L}{L}=α _LΔ T\), where ΔL= change in length, L = original length, ΔT = change in temperature, α_L = coefficient of linear expansion  

Volume Expansion:

• Volume expansion is the change in volume due to temperature.
• The volume expansion formula is given as, \(\frac{Δ V}{V}=α _VΔ T\), where ΔV= change in volume, V = original volume, ΔT = change in temperature, α_V = coefficient of volumetric expansion  

Area Expansion:

• Area expansion occurs as the change in area due to temperature change.
• The area expansion formula is given as, \(\frac{Δ A}{A}=α _AΔ T\), where ΔV= change in the area, V = original area, ΔT = change in temperature, α_A = coefficient of area expansion  

Explanation:

• The coefficient of linear expansion of iron is 11 × 10^-6 K^-1.
• The coefficient of linear expansion of brass is 19 × 10^-6 K^-1.
• The coefficient of linear expansion of copper is 16 × 10^-6 K^-1.
• The coefficient of linear expansion of lead is 29 × 10^-6 K^-1.
• Hence, from the above date, the Iron has the lowest coefficient of linear Expansion.