Brewster's Angle

Plate 22 speaks for itself: “At one angle, glare forgets how to stand up.”

The Physics

At Brewster's angle, light polarised in the plane of incidence is not reflected at all, so the reflected glare is fully polarised parallel to the surface.

tan θ_B = n₂ / n₁

• θ_B: Brewster angle from the normal, rad or °
• n₁, n₂: refractive indices of incident and second medium, dimensionless

Glass (n = 1.5): θ_B ≈ 56.3°. Water (n = 1.333): θ_B ≈ 53.1°.

Sources

• D. Brewster, Phil. Trans. R. Soc. 105, 125 (1815).

On the poster

Plate 022, “Brewster's Angle”: the pixel-art plate with its slogan “At one angle, glare forgets how to stand up.”, the key equation and the facts panel shown above. Pixelated Physics. Physics. Personified.