Circuits and Power

• Series and Parallel Circuits

  . Electrical components can be connected in series or parallel.

  . Some electrical circuits contain series and parallel parts.

  . You need to be able to calculate the currents, potential differences and resistances in d.c. series circuits.
• Series Circuits

  . There is the same current through each component.

  . The total potential difference of the power supply is shared between the comonents.

  . The total resistance of two components is the sum of the resistance of each component. This is because the current has to travel through each component in turn.

  . Adding resistors in series increases the total resistance (R) in ohms.
• Parallel Circuits

  . The potential difference across each component is the same.

  . The total current drawn from the power supply is the sum of the currents through the separate components.

  . The total resistance of two resistors is less than the resistance of the smallest individual resistor. This is because, in parallel, there are more paths for the current to take - it can take one or the other, allowing it to flow more easily.

  . Adding resistors in parallel circuits reduces the total resistance.
• Power in Circuits

  . The power of a device depends on the potential difference across it and the current flowing through it.

  . A device with a higher potential difference or current will use more energy per second than one with a lower potential difference or current, i.e. it will be more powerful.