Rubens resonance tube

A Rubens' tube for a striking demonstration of standing waves and for calculating the speed of sound in gases. Unlike Kundt's tube, it makes density differences in the gas visible from a distance as varying flame heights: a robust metal tube has 70 openings spaced 10 mm apart for the gas to escape, with a loudspeaker (2 W, 8 Ω) at one end and a regulating valve for gas cartridges at the other. It is mounted on a black base and back plate for high-contrast viewing of the flames. Tube: D = 50 mm, L approx. 860 mm; overall 86 x 14 x 23 cm; mass 4250 g. A valve cartridge and a function generator are also required.