Diffraction Calculator

What Is Light Diffraction?

Diffraction is the bending and spreading of waves when they pass through a narrow opening or past an edge. Light diffracts through slits and gratings, producing interference patterns of bright and dark fringes. This calculator finds the diffraction angle for single-slit and grating setups.

Single-Slit Diffraction

$$a \sin\theta = m\lambda$$

For a slit of width $a$, wavelength $\lambda$, and order $m$, the angle $\theta$ locates minima or maxima depending on the setup. Example: green light at $550\,\text{nm}$ through a $10\,\mu\text{m}$ slit with $m = 1$ gives $\sin\theta = 0.055$ and $\theta \approx 3.15°$.

Diffraction Grating

$$d \sin\theta = m\lambda$$

A grating with groove spacing $d$ splits light into sharp spectral orders. Each order $m$ appears at a different angle. Gratings are used in spectrometers and wavelength measurement.

Frequently Asked Questions

What does the order m represent?

The order m is an integer labeling each diffraction fringe. m = 0 is the central maximum, m = ±1 is the first side fringe, and so on.

Why does the calculator show an error for large angles?

When mλ/a exceeds 1, sin θ has no real solution. The fringe does not exist for that wavelength and slit spacing combination.

What is the difference between a slit and a grating?

A single slit produces a broad pattern with one bright central band. A grating has many parallel slits and produces sharp, well-separated spectral lines.

Does slit width affect the pattern?

Yes. A narrower slit spreads light more (larger angles) but also reduces intensity. Wider slits produce tighter patterns.

Can this calculator handle X-rays?

Yes. Enter the X-ray wavelength in nanometers or meters and the appropriate slit or grating spacing. The same equations apply to any electromagnetic wave.

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What Is Light Diffraction?

Single-Slit Diffraction

Diffraction Grating

Frequently Asked Questions

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