(a(i))[1]
the amplitude of the wave.
(a(ii))[1]
the phase difference for the points $P$ and $Q$ on the string.
(a(iii))[2]
the speed of the wave.
(b)[2]
The period of vibration of the wave is $T$. The wave advances from the arrangement shown in Fig. 6.1 for a time $0.25\,T$. On Fig. 6.1, draw the wave in its new position.
(c(i))[1]
State the phase difference for the particles labelled $X$ and $Y$.
(c(ii))[1]
Explain the following terms used for stationary waves on a string: antinode; node.
(c(iii))[1]
State how many antinodes are shown on Fig. 6.2 for this wave.
(c(iv))[1]
The period of vibration of this wave is $\tau$. On Fig. 6.2, draw the stationary wave $0.25\,\tau$ after the instant shown in Fig. 6.2.