Electrical circuits are drawn using symbols for power sources, wires and other electrical components. This is known as a schematic diagram. Electrical diagrams don't need to physically correspond to the final electric circuit, but should show the relative positioning of each component.
An electrical diagram usually starts with the power source. This can be a battery, single power cell or connection to a separate circuit, such as the mains power supply. The diagram should show the correct direction of the positive and negative terminals of each element, including the power supply.
Single cells are drawn using a long and short line with a gap between the two. To indicate a battery, several cells are drawn together. The long line of both cells and batteries represents the positive terminal. The positive terminal is considered the direction the electricity is traveling in a schematic diagram.
Some of the most common electrical components include wires, resistors and switches. Wires are represented as a straight line. A resistor is drawn as a zigzag, and open switches are indicated by a diagonal line and a gap before the wire continues. While these are the most commonly used symbols, every electrical component has a standardized symbol.