having an indicated pole (as the distinction between positive and negative electric charges); "he got the polarity of the battery reversed"; "charges of opposite sign"
marked by qualities giving the power to produce an intended effect; "written propaganda is less efficacious than the habits and prejudices...of the readers"-Aldous Huxley; "the medicine is efficacious in stopping a cough"
computer circuit consisting of an electronic sub-assembly; copper conductors are laminated on an insulating board or card and circuit components are inserted into holes and dip soldered