Cells are the building blocks of batteries. They are used to store chemical energy, which is then converted into electricity. A cell is indicated on a circuit diagram by two lines: one shorter, one longer, with the shorter one drawn thicker than the longer one. Both lines are drawn perpendicular to the wire.
A battery is used to store chemical energy, which can then be converted into electricity and released into an electric circuit. Batteries have at least one cell, but they can have many more than that. When a battery is drawn in a schematic electrical diagram, the number of cells it contains is indicated by repeating the cell symbol (described above) once for each cell in the batter. For instance, a single cell battery would be indicated by only one drawing of the cell symbol. A battery with four cells would be indicated by four instances of the cell symbol drawn in sequence.
A direct current (DC) power supply allows electricity to flow in only one direction. DC power supplies are indicated by the usual battery symbol. The longer, thinner line denotes the positive terminal of the battery, and the shorter, thicker line denotes the negative terminal.
An alternating current (AC) power supply can allow electricity to flow in either direction. An AC power supply is indicated by a circle with a squiggly line inside it. The squiggly line should look something like a tilde (~).
A fuse is a low-resistance resistor that melts when too much current is flowing through a circuit. A melted fuse breaks the circuit and stops the flow of current. A fuse is indicated by a rectangle drawn around the wire line, with its long sides running parallel to the wire. The wire line runs through the center of the rectangle.
A transformer transfers electricity from one circuit to another. A transformer is indicated by two parallel lines drawn in between two circuits. The circuits should run parallel to each other, and the lines parallel to them.
In circuits, earth is a point of zero voltage that can serve as a basis for measuring voltages at other points in the circuit. It can also protect people who may touch the circuit and prevent static electricity build up. The symbol for earth in a schematic diagram is a wire line that dead ends in three parallel lines. The lines are perpendicular to the wire, and the one that the wire dead ends on is the longest. The other two are successively shorter.