1.1. Fig. 17.1 shows the variation with distance of the displacement of a stationary wave at time t = 0.

Fig. 17.1

The period of the wave is T.

i) On Fig. 17.1, sketch a graph to show the variation of the displacement at time t =$\frac{T}{2}$.

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ii) On Fig. 17.1, show the positions of all the nodes. Label each node N.

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1.2. Stationary sound waves are formed in a tube closed at one end.

Fig. 17.2 shows three stationary wave patterns formed in the air column of the tube.

Fig. 17.2

The frequency f of the oscillations for each stationary wave is shown in Fig. 17.2.

Use Fig. 17.2 to explain how the frequency f of the sound wave depends on the wavelength $\lambda$.