Read an analogue voltmeter on the chosen scale
Connect a voltmeter across the two measured points and read a pointer using the selected full-scale voltage.
Cross-referenced from the related Cambridge IGCSE Chemistry 0620 or Physics 0625 teaching to the 0652 syllabus. Exact 0652 Core/Supplement objective coverage and this final-series course’s examiner fit still need specialist review. Written practice is self-checked and does not predict a Cambridge grade or demonstrate supervised laboratory competence.
Before you begin
- Define p.d. between two points.
- Read fractions of a scale.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
What fraction of a 0–60 scale is the mark 30?
What you will learn
- Describe parallel voltmeter connection.
- Read a stated analogue scale with range, polarity and parallax controls.
Measure across the two points
A voltmeter measures p.d. between its two connections and is connected in parallel across the component or pair of points. Its resistance is high so that it takes little current and changes the circuit as little as possible. Inserting a high-resistance voltmeter as the only series path is not the normal current-carrying arrangement.
In an isolated teacher-supervised low-voltage test, select suitable voltage terminals and a range greater than the expected reading. Start with a suitable high range for an unknown value and reduce it if appropriate. Observe d.c. polarity and the zero reading according to the instrument procedure.
Translate the shared scale
A pointer at 24 on a 0–60 scale represents 24/60 of full scale. On a 15 V range, this gives 6 V; on a 3 V range, the same pointer position gives 1.2 V. The selected range determines what the shared printed numbers mean.
Read the pointer square-on and use a supplied mirror to reduce parallax. Count the spaces between labelled marks to obtain the division value. Report sensible precision from the scale rather than inventing extra decimals, and do not treat a voltage measurement as a current measurement.
Sources for this lesson
Pause and explain
A pointer at 24 on a 0–60 scale uses a 15 V range. What is the reading?
Worked example
A pointer is at 24 on a 0–60 scale with a 15 V full-scale range. Find the p.d.
Show the worked solution
- The pointer fraction is 24/60 = 0.4.
- Full scale is 15 V.
- 0.4 × 15 = 6 V.
Answer 6 V.
Try a topic test
Choose Easy, Normal or Difficult. Save your answers and open worked review after finishing.
Test this topic →From guided practice to a new situation
Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
Read a pointer at 24 on a 0–60 scale with full scale 15 V.
Give me a hint
Find the scale fraction and apply the voltage range.
Compare my reasoning
- 24/60 = 0.4.
- Multiply 0.4 by 15 V.
- The reading is 6 V.
6 V.
Look for these in your work
- Use the range.
- State volts.
A pointer at 48 on a 0–60 scale is used on 15 V and 3 V ranges in separate trials. Find both readings.
Give me a hint
Keep the pointer fraction fixed while changing the full-scale voltage.
Compare my reasoning
- 48/60 = 0.8.
- 0.8 × 15 = 12 V.
- 0.8 × 3 = 2.4 V.
12 V; 2.4 V.
Look for these in your work
- Calculate both ranges.
- Do not treat the shared mark as a fixed voltage.
A learner inserts a high-resistance voltmeter as the sole series link and reads the pointer from the side. Explain two improvements.
Give me a hint
Check connection topology and parallax separately.
Compare my reasoning
- The meter should span the component's two terminals in parallel.
- A sole series voltmeter changes the main conducting path.
- Read square-on to reduce pointer parallax.
Connect across the component in parallel and read square-on.
Look for these in your work
- Address the circuit connection.
- Address the viewing error.
Common mistakes
- Connect across the component in parallel.
- Use the selected range.
- Read square-on and avoid unsupported precision.
What can you explain now?
How is a voltmeter connected across a component?
Compare with the explanation
In parallel between its two terminals.
The two connections define the measured p.d. rather than making the meter the main series path.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
Measure p.d. in parallel and interpret an analogue pointer with its chosen voltage range.
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.