Dispersion of White Light by a Prism

Theory

The refractive index depends on wavelength (dispersion): $n(\lambda )\approx A+B/{\lambda }^2$ (Cauchy). By Snell’s law $n_1\sin {\theta }_1=n_2\sin {\theta }_2$, violet (larger n) bends more than red.

What to observe

• The spectrum appears on the screen, from red (least deviated) to violet.

Try this

• Increase the prism’s dispersion.
• Rotate the prism and look for minimum deviation.

Also available in: Dispersão da luz branca no prisma (Português) · Dispersión de la luz blanca en un prisma (Español)