Physics

Snell’s law

Use Snell’s law to calculate refraction.

Your measurements

Number formats & units

Use decimal dots in datasets. Single values also accept decimal commas and scientific notation such as 1.2e-3 or 1.2 × 10⁻³.

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Example

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n_1\sin\theta_1=n_2\sin\theta_2

n_2=\frac{n_1\sin\theta_1}{\sin\theta_2}

\theta_2=\arcsin\!\left(\frac{n_1}{n_2}\sin\theta_1\right)

What the variables mean

Symbol	Meaning
$n_{1},\;n_{2}$	Refractive indices of the incident and second medium.
$\theta_{1},\;\theta_{2}$	Angles measured from the normal, in degrees here.

n₂ = 1.50125

Follow the example steps

Measure the angle from the normal to the surface.

A ray at 30° to the surface: θ = 30°

θ = 90° − 30° = 60° from the normal.

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Method notes

Use this for refraction at a flat boundary between isotropic media. Angles are measured from the normal, not the surface.

If solving for θ₂, a sine argument greater than 1 indicates no transmitted ray under this simple model; total internal reflection is possible.