HKDSE Waves · Ripple Tank

Ripple Tank

Explore water-wave reflection, refraction, diffraction and interference in a 3D ripple tank. Tap the surface to make ripples, place barriers or slits, and use a glass plate (shallow region) to see wavelength change.

Controls

Frequency $f$ (vibrator) 2.0 Hz

Drag to change $f$. Deep-water speed stays fixed, so $\lambda = v/f$ updates live.

Wavelength $\lambda$ (deep) 1.20 u

Amplitude 0.14

Wave source

Tip: tap / click the water surface to drop a ripple.

Barrier / slits

Slit width $a$ 0.80 u

Slit separation $d$ 1.60 u

Shallow region (glass plate)

Depth ratio $h_2/h_1$ 0.25

Strobe Slow motion Show wavefront / rays

Observation focus

Watch carefully: when frequency increases at fixed deep-water speed, the wavelength shortens ($\lambda = v/f$). In the shallow region (glass plate), the wavelength shortens while the frequency stays the same.

Live readings

Frequency $f$2.00 Hz

Wavelength $\lambda$1.20 u

Wave speed $v$2.40 u/s

$v = f\lambda$2.00×1.20

$\lambda$ (shallow)—

$v$ (shallow)—

Units are simulation units (u). Frequency is held constant across the shallow region.

Teaching presets

Challenge

Use the single-slit preset. Adjust the slit width until diffraction is most obvious (when $a \approx \lambda$).

Status: not yet

$v$ wave speed Wavefront Shallow / glass Ray / normal

Drag to rotate · Pinch/scroll to zoom · Tap water for ripples

Physics model

Deep-water speed follows $v=f\lambda$. In the shallow region, $v_2 = v_1\sqrt{h_2/h_1}$ so $\lambda_2$ shortens at the same $f$. Diffraction beyond a slit is modelled with Huygens secondary sources; double-slit interference arises from coherent superposition.

Unlike Young's light demo

This page is a textbook ripple-tank experiment in 3D: visible wavefronts, movable barriers, a glass plate for refraction, interactive surface taps, and a stroboscope — not an optical fringe calculator.