Electrodeposition is the deposition of a substance on an electrode by the action of electricity (especially by electrolysis). As a certain electric current passes though an electrolyte that contains ions of a substance, the ions begin to follow the current and adhere to the negatively charged cathode.
... be understood as "either of those element(s) of the field whose square equals b2 - 4ac". In some fields, some elements have no square roots and some have two; only zero has ...