Main menu Show/Hide Menu Introduction Summary Other Websites Series and parallel are the two types of electrical circuits. In this topic you need to know about the following: - The differences between series and parallel circuits. How resistance is affected by series and parallel circuits. The equation work done = current x potential difference The effect of changing lamps, diodes, LDRs thermistors and resistors in a circuit. Use the arrows below to continue to revise. Summary P3.1 - What determines the current in an electric circuit?