Electric chairge is the pheesical property o maiter that causes it tae experience a force whan close tae ither electrically chairged maiter. Thare are twa teeps o electric chairges – positive an negative. Positively chairged substances are repelled frae ither positively chairged substances, but attracted tae negatively chairged substances; negatively chairged substances are repelled frae negative an attractit tae positive. An object will be negatively chairged if it haes an excess o electrons, an weel itherwise be positively chairged or unchairged. The SI derived unit o electric chairge is the coulomb (C), awtho in electrical ingineerin it is an aw common tae uise the ampere-oor (Ah), an in chemistry it is common tae uise the elementary chairge (e) as a unit. The seembol Q is eften uised tae denote a chairge. The study o hou chairged substances interact is classical electrodynamics, which is accurat insofar as quantum effects can be ignored.