Use the controls below to change the apex angle, incidence and glass
Presets
Deviation δ (589 nm)—
Minimum deviation δmin—
n at 680 nm (red)—
n at 420 nm (violet)—
Angular spread (violet − red)—
Status—
Refractive index n against wavelength for the current glass, from Cauchy's relation n(λ) = B + C/λ². The steeper the curve, the more the prism spreads the colours.