1. Electric current is the flow of electric charge carriers in a conductor. Current carriers include electrons in metals, ions in electrolytes, and both electrons and holes in semiconductors. 2. The electromotive force (EMF) of a cell is the potential difference between its electrodes in an open circuit. A cell's EMF depends on the electrodes, electrolyte composition and concentration, and temperature. 3. Ohm's law states that the current through a conductor is directly proportional to the potential difference across it, provided the conductor's physical conditions remain constant. Resistance depends on the material and dimensions of the conductor.