| Electric current that flows in one direction, from positive to negative then reverses direction, from negative to positive. | |
| The process through which a liquid is turned into vapor. | |
| And organic chemical compounds made up of carbon, Coreen and fluorine atoms, usually used in refrigeration. R12 is a CFC. | |
| Two kinds of material, with different thermal expansion rates, that when attached to one another, the resulting assembly will bend in the direction of the metal that expands the least. |