expansion coefficient

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expansion coefficient

physics

Also known as: coefficient of expansion

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June 26, 2026

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Thermal expansion refers to the general increase in the volume of a material as its temperature rises. This expansion can be measured as a fractional change in length or volume per unit temperature change. For solids, a linear expansion coefficient is often used, while liquids and gases are better described by a volume expansion coefficient.1

The coefficient of expansion quantifies this change, representing the ratio of the increase in length, area, or volume per degree rise in temperature to its initial size at a specified temperature. Different materials have varying expansion coefficients due to differences in the cohesive forces between their atoms or molecules. Expansion is typically measured in linear terms, detailing the change in a unit length of a material caused by a one-degree temperature increase.213

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telescope
Reflecting telescopes
A low coefficient of expansion means that the shape of the mirror will not change significantly as the temperature of the telescope changes during the night. Since the back of the mirror serves only to provide the desired form and physical support, it does not have to…
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A low coefficient of expansion means that the shape of the mirror will not change significantly as the temperature of the telescope changes during the night. Since the back of the mirror serves only to provide the desired form and physical support, it does not have to…
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industrial glass
Thermal expansion
…inversely related to the thermal-expansion coefficient and the thickness of the piece. The thermal expansion coefficients of various oxide glasses are shown in the table of properties of oxide glasses.
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…inversely related to the thermal-expansion coefficient and the thickness of the piece. The thermal expansion coefficients of various oxide glasses are shown in the table of properties of oxide glasses.
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thermal expansion
…isometric, there may be different expansion coefficients for different crystallographic directions, and the crystal will change shape as the temperature changes.
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…isometric, there may be different expansion coefficients for different crystallographic directions, and the crystal will change shape as the temperature changes.
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mechanics of solids
Thermal strains
Here α is called the coefficient of thermal expansion. Thus, in cases of temperature change, ε_ij is replaced in the stress-strain relations above with ε_ij − ε_ij^thermal, with the thermal part given as a function of temperature. Typically, when temperature changes are modest, the small dependence of E and ν…
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Here α is called the coefficient of thermal expansion. Thus, in cases of temperature change, ε_ij is replaced in the stress-strain relations above with ε_ij − ε_ij^thermal, with the thermal part given as a function of temperature. Typically, when temperature changes are modest, the small dependence of E and ν…
Read More