Thermal Expansion

      
Introduction

/\L  =  Lo /\T

The change in length is dependent on the material used, , the original length, Lo, and the change in temperature, /\T.  is the Coefficient of Linear Expansion.  A table of common values is listed below.

Coefficients of Expansion at 20oC
Material	Coefficients of Linear Expansion, , (oC) -1	Coefficients of Volume Expansion, , (oC) -1
Solids
Aluminum	25 x 10 -6	75 x 10 -6
Brass	19 x 10 -6	56 x 10 -6
Iron or Steel	12 x 10 -6	35 x 10 -6
Lead	29 x 10 -6	87 x 10 -6
Glass (Pyrex)	3 x 10 -6	9 x 10 -6
Glass (Ordinary)	9 x 10 -6	27 x 10 -6
Quartz	0.4 x 10 -6	1 x 10 -6
Concrete and Brick	approx 12 x 10 -6	approx 36 x 10 -6
Marble	1.4~3.5 x 10 -6	4~10 x 10 -6
Liquids
Gasoline		950 x 10 -6
Mercury		180 x 10 -6
Ethyl alcohol		1100 x 10 -6
Glycerin		500 x 10 -6
Water		210 x 10 -6
Gases
Air (and most other gases           at atmospheric P)		3400 x 10 -6

The Coefficient of Linear Expansion varies slightly with temperature.  This is why thermometers of different materials do not always agree between the calibration points.  If the temperature range is not too great, the change in can be ignored.

/\V  =  Vo /\T	The change in volume is dependent on the material used, , the original volume, Vo, and the change in temperature, /\T.  is the Coefficient of Volume Expansion.  A table of common values is listed above.
/\  =  - o /\T	If the volume increases, the density must decrease.  Remember, Density is mass/volume and the mass does not change with temperature.

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