Measuring potential difference (voltage) and current

A potential difference across an electrical component is needed to make an electric current flow in it. Cells or batteries often provide the potential difference needed.

Potential difference is often called voltage. It is also known as electromotive force. Note that this is not really a ‘force’, and it is measured in volts (not newtons).

Measuring potential difference (voltage)

  • potential difference is measured in volts, V
  • the potential difference across a component in a circuit is measured using a voltmeter
  • the voltmeter must be connected in parallel with the component
Circuit with a cell, switch and lamp. A voltmeter is connected in parallel with the lamp.

Measuring current

  • current is measured in amperes (amperes is often abbreviated to amps or A)
  • the current flowing through a component in a circuit is measured using an ammeter
  • the ammeter must be connected in series with the component
Circuit with a cell, switch, lamp and ammeter connected in series.