Microwaves Shake Water
All scenes › Chapter 2 Waves in the Box
Waves Trapped by Metal Walls
Metal walls bounce the waves and keep them inside
View in 3DWaves trapped by metal walls
The waves come in through a small window on the right wall. All six sides of the inner box are metal, so the waves bounce off every wall like a ball (the yellow lines). They can’t get out, so they keep bouncing around inside. So what shape are these bouncing waves?
Why?Metal is full of electrons that can move freely. When a wave hits the metal, those electrons move right away and send the wave back. To a wave, metal is like a mirror.
Learn moreThe yellow lines show just a few directions the waves travel. Real waves fill the whole box and cross it millions of times a second.
- Depth of the inner box (example)
- 32.5 cm
textbook formulas · example oven cavity 31.5 × 21 × 32.5 cm
View this scene in 3D →Read more
More in the series
Wavelength, standing waves and the properties of water are calculated with textbook formulas. The standing-wave pattern is a simplified sum of the metal box’s resonant modes; water’s properties come from the Debye model (water at 20 °C). In the 3D view, waves and molecules move far slower than in real life, and the water molecule is an enlarged model.