Question

A standing wave between the oscillator and the pulley is observed what is the mode number (the number of antinide; the higher harmonics) if the standing wave?

Answer 1

Antinodes - points with the maximum vertical displacement of a standing wave. The number of antinodes:

$$A=\frac{2L}{\lambda}.$$

To calculate the number, length of a string and the wavelength are required.

The number of observed harmonics equals to the number of antinodes:

$$H=A.$$

Finally, the mode number is represented by the number of the harmonics or the number of antinodes, that is why

$$M=H=A=\frac{2L}{\lambda}.$$