Helmholtz's Bottle
Plate 087 Physics Poster
Plate 87 speaks for itself: “A bottle hums one note.”
The Physics
Blow across a bottle and the air in its neck bounces like a mass on the spring of the air inside. This one resonance sets the note.
f = (c / 2π) √(A / (V L_eff))
- f: resonant frequency, Hz
- c: speed of sound, m s⁻¹
- A: neck cross-section, m²
- V: cavity volume, m³
- L_eff: effective neck length, m
The air in the neck moves like a mass on a spring. c = 343 m/s.
Sources
- H. von Helmholtz, On the Sensations of Tone (1863).
On the poster
Plate 087, “Helmholtz's Bottle”: the pixel-art plate with its slogan “A bottle hums one note.”, the key equation and the facts panel shown above. Pixelated Physics. Physics. Personified.
Shipping calculated at checkout by destinationMade to order, ships in 2–5 business days
Field notes
查看全部-
Why Does a Third Polarizer Let Light Through? T...
Cross two polarizing filters and the view goes black. Slide a third filter between them at 45° and light reappears, about one eighth of the original. Adding a filter lets...
Why Does a Third Polarizer Let Light Through? T...
Cross two polarizing filters and the view goes black. Slide a third filter between them at 45° and light reappears, about one eighth of the original. Adding a filter lets...
-
What Is the Photon Sphere, and What Did the Eve...
Near a black hole there is a radius where gravity bends light into a circle: the photon sphere, at r = 3GM/c² for a non-spinning hole. It is unstable, so...
What Is the Photon Sphere, and What Did the Eve...
Near a black hole there is a radius where gravity bends light into a circle: the photon sphere, at r = 3GM/c² for a non-spinning hole. It is unstable, so...
-
Fermions vs Bosons: What Is the Difference?
Every particle in nature is either a fermion or a boson. Fermions, like electrons and quarks, have half-integer spin and obey the Pauli exclusion principle. Bosons, like photons, have integer...
Fermions vs Bosons: What Is the Difference?
Every particle in nature is either a fermion or a boson. Fermions, like electrons and quarks, have half-integer spin and obey the Pauli exclusion principle. Bosons, like photons, have integer...
