(i) Describe the difference between alternating current (a.c.) and direct current (d.c.). (ii) State a source of direct current. __

(i) The main difference between alternating current (a.c.) and direct current (d.c.) is the direction of flow of electric charge. In a.c., the electric charge changes direction periodically, while in d.c., the electric charge flows in a constant direction.<br /><br />(ii) A common source of direct current is a battery or a cell.