Pearson Edexcel · GCSE · Physics
Course version: 1PH0 · Version from Sept 2016
Recall that a voltmeter is connected in parallel with a component to…
Full specification wording
Topic 10 – Electricity and circuits: 10.4 Recall that a voltmeter is connected in parallel with a component to measure the potential difference (voltage), in volt, across it
Potential difference, often called voltage, is measured with a voltmeter connected in parallel with the component being tested.
Checked against the Pearson Edexcel 1PH0 specification (opens in a new tab) on .
- Point 4 of 39
Study notes
From the checked teaching notes for this specification point.
The idea
Potential difference, often called voltage, is measured with a voltmeter connected in parallel with the component being tested. Placing the voltmeter across the component means both its terminals touch the two ends of that component, so the voltmeter experiences the same potential difference as the component and reads it directly. The unit of potential difference is the volt (V). A voltmeter has a very high resistance so that only a tiny current diverts through it, which keeps the circuit's behaviour almost unchanged. Contrast this with an ammeter, which is connected in series to measure current. When reading a circuit diagram, check that the voltmeter symbol sits on a branch alongside the component, not in the main line.
What earns the marks
- States that a voltmeter is connected in parallel with the component whose potential difference is measured.
- States that potential difference is measured in volts.
- Explains that connecting in parallel places the voltmeter across the same two points as the component.
- Distinguishes the voltmeter's parallel connection from the ammeter's series connection.
- Recognises that a high-resistance voltmeter draws very little current so the reading is accurate.
Common mistakes and how to put them right
Places the voltmeter in series with the component.
Put it right: Connect it in parallel across the component instead.
Gives the unit of potential difference as the ampere.
Put it right: State that potential difference is measured in volts.
Connects the voltmeter across the whole circuit when a single component is being measured.
Put it right: Place it across that component only.
Exam tips
- Look for the voltmeter symbol drawn on a branch beside the component, which signals a parallel connection.
- Match the quantity to its instrument and unit: potential difference–voltmeter–volt, current–ammeter–ampere.
- Remember the high resistance of a voltmeter explains why it barely alters the circuit.
Try the lesson
The start of the Topic 10 – Electricity and circuits: 10.4 Recall that a voltmeter is connected in parallel with a component to measure the potential difference (voltage), in volt, across it lesson, made from checked teaching notes for this specification point.
Have a go first
A student wants to measure the potential difference across a resistor in a circuit. How should the voltmeter be connected?
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