Quick Answer: The Wave Motion Apparatus (18 Pulleys) is a hand-cranked transverse wave demonstrator in which 18 eccentric cams on one shaft lift 18 vertical rods tipped with coloured balls. Turning the crank sends a continuous wave along the row.
Last updated: October 2026
Key Features
18 eccentric pulleys (cams) set at offset angles along one shaft
18 vertical steel rods with high-visibility moulded balls
Manual hand crank on low-friction bearings
Powder-coated sheet steel base
Crank speed controls frequency, so wave speed can be varied by hand
Technical Specifications
Specification
Value
Mechanism
18 sequentially offset eccentric cams
Indicators
18 vertical steel rods with moulded balls
Drive
Manual hand crank with bearing support
Frame
Powder-coated sheet steel base
Wave type
Continuous transverse travelling wave
Dimensions (L x W x H)
Approx. 450 mm x 120 mm x 300 mm
Weight
Approx. 2.2 kg
About This Product
Cranking slowly shows each rod rising and falling in place while the wave shape moves along, the defining feature of a transverse wave. Stopping the crank freezes the pattern so students can measure wavelength and amplitude with a ruler and pick out crests, troughs and phase differences, and cranking faster shows how frequency affects the wave.
Frequently Asked Questions
What makes the wave in the Wave Motion Apparatus?
Each of the 18 eccentric cams is set a little further round than its neighbour, so the rods resting on them rise and fall in sequence and form a travelling transverse wave.
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