PhysicsUKINTERACTIVE LAB
CHARGE · MEASURE · DISCOVER

Electric Field Lab.

FREE LAB

Build a field. Place a probe. Follow your question.

Select a component using the inspector. Edit its coordinates or use arrow keys on the canvas to move it; Shift makes smaller changes. Drag objects directly. Ruler endpoints can be dragged separately. Space starts or pauses motion.

YOUR ELECTRIC FIELD WORKSPACEDrag components. Measure at any point.
0ns
Positive to negative. Field arrows show direction.

MAKE IT YOUR INVESTIGATION

Move probes A and B to compare potential, field strength and work. Add more probes to map your own configuration.

A LITTLE HELP GETTING STARTED

Make the invisible
measurable.

  1. Build: add charges, a dipole, plates, probes, rulers or screens from the left. Select a component to edit exact coordinates, charge, dimensions or voltage. Drag to reposition; use arrow keys on the focused canvas for precise movement.
  2. Measure: probes A and B define a voltmeter and a line profile. Further probes map the field. Record snapshots, choose graph axes and export results. Distances are measured from charge centres.
  3. Launch: set the particle species, mass, charge, speed and direction. Pause or step, keep up to four comparison traces, and place a detector screen. Apparatus edits reset motion; saved traces retain their original settings.
  4. Oil drop: run with the field off to time a fall between the microscope marks. Apply a voltage and reverse direction if needed. Time a terminal rise or balance the drop; then record an inferred charge. Use several unknown drops to investigate charge quantisation.

Field model: charges are fixed uniformly charged spherical shells; outside, E = kQ/r² and V = kQ/r. No induced charge redistribution is modelled. Probe charge does not disturb the sources. Arrows and representative field lines show direction and shape; arrow lengths and line density are illustrative. Use probe readings for quantitative field strength. Potential colours use a changing symmetric scale.

Plates: extended plates are an ideal infinite pair, with zero potential at the midplane. The drawing shows a section; there are no end effects. Finite beam plates use a sharp field boundary with no fringing. Potential is unavailable beyond their ends; a profile crossing such an edge cannot be used for work/energy comparisons. Plate voltage is maintained by an ideal supply; capacitance assumes negligible fringing and a dielectric filling the gap.

Particles: classical point test particles, no mutual interactions or radiation. Surfaces absorb particles. A numerical trajectory stops above 0.1c or if it cannot resolve the field; reduce speed/voltage or increase source size. Keep changes small near sources. Motion playback is slowed, while the clock shows simulated time.

Oil drop: an isolated spherical drop with weight, optional air buoyancy, electric force and Stokes drag. The microscope is a magnified window; plate separation is set independently. No Brownian motion, evaporation or slip correction. Gate readings are model measurements without random instrument error; compare repeated drops and discuss real measurement uncertainty. The drop can leave the microscope while remaining between the plates. Reset motion returns it to the window without changing its charge.

Curriculum: core AQA 3.7.3 and OCR A 6.2.1–4. Millikan’s experiment is AQA Turning Points 3.12.1.4, and an extension for OCR A. These virtual investigations support practical reasoning; they do not certify a required practical or PAG.

Files: saves include apparatus, oil settings and recorded results. Local recovery is automatic when storage is available. Playback and kept trajectory drawings are not restored.