The Fountain Effect

Plate 65 speaks for itself: “Heat it, it rises.”

The Physics

Heating superfluid helium behind a fine porous plug draws more superfluid in through the plug, and the pressure rise can jet liquid out of the top.

ΔP = ρ s ΔT

• ΔP: fountain pressure, Pa
• ρ: density, kg m⁻³
• s: specific entropy, J kg⁻¹ K⁻¹
• ΔT: temperature difference, K

Heat draws superfluid in via the plug. The liquid jets out of the top.

Sources

• J. F. Allen, H. Jones, Nature 141, 243 (1938).

On the poster

Plate 065, “The Fountain Effect”: the pixel-art plate with its slogan “Heat it, it rises.”, the key equation and the facts panel shown above. Pixelated Physics. Physics. Personified.