PPolySim OS

Double-Slit Experiment

The experiment at the heart of quantum weirdness. See how two slits create bright and dark interference fringes, shaped by each slit's diffraction envelope.

Double-Slit ExperimentLive

Controls

The iconic experiment: two slits create interference fringes, modulated by each slit's diffraction envelope.

Presets

▶ Run in Python

Data Inspector

Fringe spacing∝ λ/d
Envelope∝ λ/a
Regimeinterference-dominated

Governing equation

Reading this result: Two-slit interference sets the fine fringe spacing (∝ λ/d) while single-slit diffraction sets the envelope (∝ λ/a); here about 10 bright fringes fit under the central peak.

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How it works

The screen intensity combines two-slit interference, cos²(πd·sinθ/λ), with the single-slit diffraction envelope, sinc²(πa·sinθ/λ). Change the slit separation, slit width, and wavelength to watch the fringe spacing and envelope respond exactly as in the real experiment.

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Frequently asked questions

Is this double slit experiment tool really free?
Yes. Double-Slit Experiment runs entirely in your browser using your device's own compute, so local use is free forever. You only pay Compute Tokens if you scale a job to the cloud.
Do I need to install anything?
No. Everything runs client-side in a modern browser — no downloads, no license, no account required to start.
Can I save or share my simulation?
Create a free account to save projects, and use a shareable embed or minted DOI to publish a live, interactive version anywhere.
How accurate are the results?
The solver uses established numerical methods, but results are for research and educational purposes and should be validated against experiment or professional review before you rely on them.