Phase velocity of rope waves

Principle

A quadrangular rubber rope is inserted through the demonstration motor and a linear polarised fixed wave is generated. With the help of a stroboscope, the frequency and the wave length are determined. Then the phase velocity of ropewaves with a fixed tensile stress is ascertained. Subsequently, the mathematical relationship between the phase velocity of the rope and the tensile on the rope is examined.

Benefits

• Difficult physics of phase velocity presented in a simple way
• High-precision results thanks to use of special rope and stroboscope
• Large and easy to see wave crests and troughs

Tasks

1. With constant tensile stress, the frequency f, which depends on the wavelength λ of the wave that propagates itself along the rope. The frequency is plotted as a function of 1/λ. From this graph, the phase velocity c is determined.
2. The phase velocity c of the rope waves, which depends on the tensile stress on the rope is to be measured. The quadrant of the phase velocity is plotted as a function of tensile stress.

What you can learn about

• Wavelength
• Phase velocity
• Group velocity
• Wave equation
• Harmonic wave