Measuring the resistance of a filament lamp
I can find the resistance of a filament lamp by measuring the current and p.d. for a suitable range of p.d.
Measuring the resistance of a filament lamp
I can find the resistance of a filament lamp by measuring the current and p.d. for a suitable range of p.d.
These resources will be removed by end of Summer Term 2025.
Lesson details
Key learning points
- An appropriate range of p.d. values includes 0 V and the maximum p.d. of the lamp and at least four other readings.
- For electricity investigations, it is good practice to take many more than the minimum number of measurements.
- After plotting a graph, extra readings could be taken to fill gaps or to check possible errors.
- Plots that lie off the best fit line are possible errors that need to be checked.
- The resistance of a filament lamp is calculated from an I–V graph using pairs of readings and the equation R = V ÷ I.
Keywords
Filament lamp - a type of lamp that uses a hot wire to emit light
Variable resistor - a resistor that can be easily changed to any value in its range
Range - the minimum to maximum possible values in an experiment
Repeat reading - when a measurement is taken again to improve the experiment
Best fit line - a line that shows the underlying trend of a set of results on a graph, it can be straight or curved
Common misconception
The terms current, voltage, resistance, energy and power, together with the properties of each, are often mixed up.
As each term is introduced during this lesson, spend a few moments checking pupils’ understanding.
To help you plan your year 10 physics lesson on: Measuring the resistance of a filament lamp, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your year 10 physics lesson on: Measuring the resistance of a filament lamp, download all teaching resources for free and adapt to suit your pupils' needs.
The starter quiz will activate and check your pupils' prior knowledge, with versions available both with and without answers in PDF format.
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The assessment exit quiz will test your pupils' understanding of the key learning points.
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Explore more key stage 4 physics lessons from the Circuit components unit, dive into the full secondary physics curriculum, or learn more about lesson planning.
Equipment
Power supply (or battery pack), filament lamp, variable resistor, electrical leads, ammeter and voltmeter.
Content guidance
- Risk assessment required - equipment
Supervision
Adult supervision required
Licence
Starter quiz
6 Questions



Exit quiz
6 Questions
measures the p.d. across the lamp
measures the current through the lamp
changes the p.d. across the lamp
get brighter when more current flows

