National 5PhysicsSQARevision NotesElectricityPractical Electrical & Electronic CircuitsMeasuring Current, Potential Difference & Resistance

Measuring Current, Potential Difference & Resistance (SQA National 5 Physics): Revision Note

Exam code: X857 75

Katie M

Written by: Katie M

Reviewed by: Caroline Carroll

Updated on

Measuring current, potential difference & resistance

Measuring current

  • Current can be measured using an ammeter

  • Ammeters must be connected in series with the component being measured

Ammeter in series

Simple circuit diagram showing a battery, a lamp, and an ammeter connected in series with the lamp.
An ammeter can be placed in series with a component to measure the current through it

Measuring potential difference

  • Potential difference (or voltage) is measured using a voltmeter

  • A voltmeter is always set up in parallel with the component being measured

Voltmeter in parallel

Simple circuit diagram with a battery, lamp, resistor, and voltmeter in parallel with the resistor.
Potential difference can be measured by connecting a voltmeter in parallel with the component

Examiner Tips and Tricks

When you are building a circuit in class, always connect the voltmeter last. Make the whole circuit first and check it works, and then connect the voltmeter so that the leads are on each side of the component you are measuring. This will save you a lot of time waiting for your teacher to troubleshoot your circuit!

Potential difference describes a difference between two points; therefore, the voltmeter has to be connected between two points in the circuit.

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    Author
    Reviewer
    Katie M

    Author: Katie M

    Expertise: Physics Content Creator

    Katie has always been passionate about the sciences, and completed a degree in Astrophysics at Sheffield University. She decided that she wanted to inspire other young people, so moved to Bristol to complete a PGCE in Secondary Science. She particularly loves creating fun and absorbing materials to help students achieve their exam potential.

    Caroline Carroll

    Reviewer: Caroline Carroll

    Expertise: Physics & Chemistry Subject Lead

    Caroline graduated from the University of Nottingham with a degree in Chemistry and Molecular Physics. She spent several years working as an Industrial Chemist in the automotive industry before retraining to teach. Caroline has over 12 years of experience teaching GCSE and A-level chemistry and physics. She is passionate about creating high-quality resources to help students achieve their full potential.