← Back to Lab
Physics · 4.3 Electric circuits · Paper 6 practical

Circuit Builder. Wire it.

Build series and parallel circuits, swap components, change values, and watch the ammeter and voltmeter respond in real time. Bulbs glow based on dissipated power. Compare current and voltage rules for series vs parallel.

0625 Topic 4.2.4 — Current 0625 Topic 4.2.5 — Resistance 0625 Topic 4.3.2 — Series & parallel
Series circuit — same current at every point. The voltages across each component add up to the EMF.

Power supply

6.0
0.5

Components in the loop

Live circuit

Total current I
0.50 A
Total resistance R_total
12.0 Ω
Terminal p.d. across battery
5.75 V
Power dissipated
3.00 W
Series rule: I is the same at every point. V_total = V₁ + V₂ + V₃ + ...
📋 Method (Cambridge ATP guidance)

For each circuit topology you build:

  1. Identify the independent and dependent variables in your investigation.
  2. Place an ammeter in series with the component whose current you want to measure.
  3. Place a voltmeter in parallel with the component whose potential difference you want to measure.
  4. Use the switch to close the circuit only when taking a reading, to prevent the components heating up.
  5. Record values in a table; calculate the resistance of each component using R = V / I.

Series rules: current is the same everywhere; voltages add to the supply.

Parallel rules: potential difference across each branch is the same; branch currents add to the total current.

⚠ Sources of error & precautions
  • Wire heating — current heats the wires, raising their resistance. Open the switch between readings.
  • Loose connections — clip leads tightly so contact resistance is small.
  • Meter zero error — check both meters read zero with the switch open.
  • Polarity — match the positive terminal of the meter to the positive side of the supply.
  • Ideal meter assumption — a real voltmeter has finite resistance; the simulation treats it as ideal.
🧪 Apparatus list
  • Low-voltage DC power supply (or cells in a holder)
  • Switch
  • Ammeter (in series) and voltmeter (in parallel)
  • Fixed and variable resistors, filament bulbs
  • Connecting leads with crocodile clips
  • Circuit board / breadboard
🎯 Syllabus reference (0625)
  • 4.2.4 Electric current — recall that conventional current flows from + to −; measure current using an ammeter in series.
  • 4.2.5 Electromotive force, p.d. and resistance — use R = V/I; recall that p.d. is measured by a voltmeter in parallel.
  • 4.3.2 Series and parallel circuits — recall that the current is the same at every point in a series circuit; recall that the p.d. across components in parallel is the same; recall that branch currents add to the total.
  • 4.4.1 Power — recall P = IV.

Ask the lab assistant