Measuring voltage in circuits
Voltage is marked on cells and electrical components such as bulbs and kettles, but what does it mean?
It tells you how much electrical energy has been converted into other forms of energy.
Voltage is measured in volts, V, with a voltmeter.
Voltmeters are always connected in parallel.
This is because it is measuring the difference in energy between the two points it is connected across.
The positive terminal of the voltmeter is connected closest to the positive terminal of the battery.
Key points
When measuring voltage:
- Voltage is measured in volts, V.
- Voltage is measured using a voltmeter.
- A voltmeter is connected in parallel.
Measuring voltage in series circuits
You can investigate voltage across cells and lamps in a series and parallel circuit by connecting the following circuits.
Put one voltmeter in position V1 and record the reading in a suitable table.
Then move the voltmeter to position V2 and repeat and then to position V3.
Results
V1 = 3.0V
V2 = 1.5V
V3 = 1.5V
Conclusion
The voltage across each component in a series circuit adds up to equal the voltage across the cells.
Measuring voltage in parallel circuits
Results
V1 = 3.0V
V2 = 3.0V
V3 = 3.0V
Conclusion
The voltage across each branch of a parallel circuit equals the voltage across the cells.