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For Students · Snell's Law

Snell's Law for a laser pointer

Built for students learning it for a class or exam. See the concept move instead of memorizing formulas — and check your homework intuition. Simulate a laser pointer live below — adjust the inputs and watch it respond, right in your browser.

Snell's Law — RefractionLive

n₁ sin θ₁ = n₂ sin θ₂

Controls

Light bends when it crosses between media. Going into a slower medium it bends toward the normal; going the other way past the critical angle it reflects entirely.

Presets

Incidence angle

Index n₁ (top)

Index n₂ (bottom)

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Data Inspector

n₁ → n₂1 → 1.5

Critical anglen/a

Snelln₁sinθ₁ = n₂sinθ₂

Governing equation

n_{1} sin θ_{1} = n_{2} sin θ_{2} : 1 sin 4 0^{\circ} = 1.5 sin θ_{2}, θ_{c} = arcsin \frac{n _{2}}{n _{1}} = n/a

Reading this result: Into a denser, slower medium: the ray bends toward the normal, so the refracted angle is smaller than the incidence angle.

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Frequently asked questions

Is this good for students?: Yes — this version of "Snell's Law for a laser pointer" is framed for students learning it for a class or exam. See the concept move instead of memorizing formulas — and check your homework intuition.
Do I need to install anything?: No. It runs in any modern browser, free, with no account required.