Electrical circuits can be arranged in series, in parallel or in a hybrid conformation. A series circuit gives current a single path through which to flow. The current thus goes through the appliances in the circuit sequentially. In contrast, a parallel circuit has multiple branches, each of which is a path through which current can flow. For example, four wires connecting one end of a battery to the other end of the battery make up a parallel circuit.
Look up any schematic symbols with which you are not familiar. For example, zigzag lines are resistors.
See if the circuit is in series, parallel or a combination of the two. It is important to figure this out because series and parallel circuits have different rules regarding voltage, current and resistance.
Reduce the circuit to a pure series or pure parallel circuit if it is a hybrid circuit. Combine resistors (such as appliances) to do this. For example, if a circuit is mostly series but has two resistors in parallel with each other, find the combined resistance of those two resistors and redraw the circuit with one new resistor rather than two. The new resistor has the combined resistance that you calculated.
Calculate any unknown voltage, current and resistance values using Ohm's Law, which states that the voltage (V) of a device or circuit is the product of the current (I) flowing through that device or circuit and the resistance (R) of the device or circuit. In equation format, Ohm's Law is: V = IR.