Linear Expansivity

Expansivity is the increase in the length of a substance when its temperature increases by one kelvin or degree Celsius.

Linear expansivity (α) of a substance is defined as the increase in length of a substance, per unit length of the substance, per degree rise in temperature.

Mathematically,

linear expansivity  = α

\(\scriptsize α = \normalsize \frac {Change \: in \: Length}{Original \: Length \: \times \: temperature \: rise}\)

If L₁ = the original or initial length

θ₁ = Original or initial temperature

L₂  = New Length

θ₂ = New temperature

α = Linear expansivity

\( \scriptsize Then \;  α = \normalsize \frac {L_2\: – \:L_1}{L_1 \: \times \: (\theta_2\: – \: \theta_1\ ) }\)

The S.I unit is per kelvin \( \scriptsize K^{-1} \) or per degree Celsius \( \scriptsize ^{०} C^{-1} \)

For a change in length,