ABSTRACT
This chapter talks about direct current (DC) circuits that contain resistors and the basic terms used such as charge, current, voltage, resistance and power. Current is defined as the rate of movement of charge in a circuit. When there is a current through a circuit then charge is continuously moved through it. Energy has to be continually supplied to keep the charge moving. The rate at which this energy is required is called the power. When there is a current passing through a component, then all the charge that enters it over a period of time must equal all the charge that leaves it. Thus the rate at which charge enters a component, that the current, must equal the rate at which current leaves the component. The idea can be extended to an electrical circuit; the total current entering any junction in a circuit must equal the total current leaving it. This is called Kirchhoff's current law.
