Ripple Tank: Waves, Reflection, Diffraction & Refraction
The 2D wave equation solved live on a grid — nothing scripted. Reflection happens because ripples genuinely bounce off barrier cells, diffraction because a gap is just an opening, refraction because the shallow shelf simply slows the waves. Seven scenes cover plane waves, an angled reflector, narrow vs wide gaps, the Young double-slit experiment, a refracting shelf, and two-point interference, with a one-way wave generator, absorbing beaches on every wall, slow motion, a stroboscope, and a 10 cm grid for measuring wavelength against v = fλ.
Bright bands = crests, dark bands = troughs — like the light table under a real tank. The dark bar on the left is the wave generator: it launches waves one way, left to right, and swallows anything that comes back. Every wall has an absorbing beach, so what you see is each phenomenon by itself — no echoes. Brass = barriers. Gridlines are 10 cm apart, for measuring λ.
A straight dipper sends plane waves down the tank.
Pause or strobe the tank and measure the crest spacing against the 10 cm grid — that distance is the wavelength. Change f and check that λ = v/f, with v fixed by the water.
What Each Variable Means
Wave speed. How fast the wavefronts travel, in cm/s here. Set by the water depth, NOT by the dipper.
Frequency. How many waves the dipper makes each second, in hertz (Hz). Set by the source, and unchanged by reflection or refraction.
Wavelength. The distance between two adjacent crests, in cm. Measure it against the 10 cm grid.