explai what is Expansion of solid ?
and give example ?

A:

 Thermal expansion is the tendency of a matter to change in volume in response to a change in temperature. When a substance is heated, its constituent particles begin moving and become active thus maintaining a greater average separation. Materials which interact with increasing temperature are rare ; this effect is limited in size, and only occurs within limited temperature ranges. The degree of expansion divided by the change in temperature is called the material's coefficient of thermal expansion and generally varies with temperature.