Diffraction Grating Equation
Enter your known values, leave one input blank, and solves for the missing one. Try different units for next level excitement!
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A grating is thousands of slits acting in concert: constructive interference survives only at angles where neighboring slits' paths differ by exactly m whole wavelengths, so each wavelength gets its own sharp beam. A grating ruled at 600 lines/mm (d = 1.667 μm) throws 550 nm green light to arcsin(550/1667) ≈ 19.3° in first order. This is the dispersing heart of most spectrometers — and of the rainbow flash from a CD's surface, whose data tracks form an accidental grating.
Diffraction Grating Equation
Where
- = Diffraction order
- = Wavelength
- = Line spacing
- = Diffraction angle
Missing one of these? Work it out first, then come back
- Diffraction order — Thin-Film Constructive Interference (Bright Reflection), Thin-Film Destructive Interference (Dark Reflection)
- Wavelength — Wave Speed (v = fλ), Double-Slit Fringe Spacing
- Line spacing — Double-Slit Fringe Spacing, Speed, Distance & Time
- Diffraction angle — Snell's Law of Refraction, Critical Angle for Total Internal Reflection