O-Level Physics Wave Speed Practical: Ripple-Tank Video Measurements

A ripple pattern gives a distance between crests; a video also gives a time record. Use both to estimate wave speed from frequency multiplied by wavelength. The challenge is to measure distances and times in the actual experiment, rather than in an enlarged image or slow-motion playback.

This guide uses a trainer-approved ripple tank at fixed water depth, with a camera recording a steady wave train. The trainer checks the tank, lighting and electrical arrangement for use near water. Begin with the general lab safety guide.

Plan the measurement

The 2026 O-Level Physics syllabus, 6091, includes wave-speed investigations in its practical scope on pages 31-32. Oak National Academy's ripple-tank lesson provides a related measurement example; its UK course label does not define Singapore assessment requirements.

Use a clear region before reflected waves significantly interfere with the incident pattern. Keep water depth, generator condition and camera position fixed for a run. A distance calibration must refer to the plane being measured. A ruler beside an enlarged projection or at a different depth cannot automatically supply the water-surface scale.