A circuit diagram is a simplified schematic representation of the components of an electrical circuit. A good circuit diagram shows the relative position of each of these components, how they are interconnected and other operational parameters of the circuit.
Circuit diagrams show whether components are connected in series or parallel. This enables the calculation of the amount of current and potential flowing through each branch of the circuit. Circuit diagrams also show the direction of current flow in the circuit and whether this current is alternating or direct.
A direct current source is usually denoted as a battery, with long and short horizontal lines separated by a slight gap. The conventional current flows out of the long side and back into the short side. An alternating current source is represented as a circle enclosing a single sinusoidal wave. The two terminals of this kind of source are equivalent if the current is completely symmetrical. If there is a net current flow in either direction, this is denoted through a serial combination of an AC source and a DC source.
Other circuit components that can be denoted on a diagram include measurement devices, such as ammeters and voltmeters, which measure current intensity and potential difference, respectively.