Chimella: Hot Chocolate Effect
Optics, Waves & Sound arc, page 125 of 193. Back to The Pixelated Physics Universe
Who they are
Chimella has one line, and says it often: “Tap the mug. hear the bubbles leave.”
Chimella is a character of the Optics, Waves & Sound arc: drawn in pixels, ruled by one piece of real physics, and never allowed to break it.
The physics
Hot chocolate effect: tapping pitch rises as bubbles leave, because bubbles lower the sound speed.
$$ \begin{gathered} \frac{1}{\rho c^{2}} = \frac{1-\phi}{\rho_l c_l^{2}} + \frac{\phi}{\rho_g c_g^{2}} \\ f \propto c \end{gathered} $$
| Symbol | Meaning | SI unit |
|---|---|---|
| $\rho$ | mean density of the bubbly liquid | kg/m^3 |
| $c$ | sound speed in the mixture | m/s |
| $\phi$ | gas volume fraction | — |
| $\rho_l,\ c_l$ | density and sound speed of the liquid | — |
| $\rho_g,\ c_g$ | density and sound speed of the gas | — |
| $f$ | resonant (tap) frequency | Hz |
Sources
Crossovers
Chimella meets Sonara (Sonoluminescence). Chimella's bubbles lower the speed of sound in hot chocolate. Sonara's single bubble collapses in a sound field. Sound and bubbles pull on each other in both mugs.
Chimella meets Levitah (Held by Sound). Levitah uses the force of sound to hold objects. Chimella uses bubbles to change the speed of sound itself. Both are acoustics in the everyday kitchen and lab.
Wear the lore
- Chimella, the Hot-Chocolate Bell Mug
- Related infographic poster: Minnaert's Bubble – Plate 090 Physics Poster
Concept keywords: Hot Chocolate Effect, Chimella, Optics, Waves & Sound, physics lore, Pixelated Physics