has the highest value of specific heat capacity. For this reason it is used as a coolant in power stations and reactors. - - - - Unit Heat and thermodynamics Liquids , have less intermolecular forces than solids and hence they expand more than solids. This is the principle behind the mercury thermometers.
In the case of gas molecules, the intermolecular forces are almost negligible and hence they expand much more than solids. For example in hot air balloons when gas particles get heated, they expand and take up more space. The increase in dimension of a body due to the increase in its temperature is called thermal expansion. The expansion in length is called linear expansion .
Similarly the expansion in area is termed as area expansion and the . . Thermal expansion of solids, liquids and gases Thermal expansion is the tendency of matter to change in shape, area, and volume due to a change in temperature. All three states of matter (solid, liquid and gas) expand when heated.
When a solid is heated, its atoms vibrate with higher amplitude about their fixed points. The relative change in the size of solids is small. Railway tracks are given small gaps so that in the summer, the tracks expand and do not buckle. Railroad tracks and bridges have expansion joints to allow them to expand and contract freely with temperature changes.
It is shown in Figure . Figure . Thermal expansions L T L o T = T o + T T o L o (a) Linear expansion T A o