State the conditions necessary for stationary waves to form.
The vibrator oscillates at $250\,\text{Hz}$ and a transverse wave travels along the string with a speed of $12\,\text{m s}^{-1}$. The wave is reflected at the pulley and a stationary wave forms on the string. At time $t = t_1$, the string has maximum displacement. Calculate the distance AB.
One end of a string is fixed to a vibrator. The other end is passed over a pulley and a load is attached so that the string is stretched, as shown in Fig. 4.1. The vibrator frequency is set to $250\,\text{Hz}$ and a transverse wave travels along the string with a speed of $12\,\text{m s}^{-1}$. The wave is reflected at the pulley and a stationary wave forms on the string. Fig. 4.2 shows the string between points A and B at time $t = t_1$. At time $t = t_1$, the string has maximum displacement.
On Fig. 4.2, draw the string between A and B at the following times: 1. $t = t_1 + 2.0\,\text{ms}$ (call this P), 2. $t = t_1 + 5.0\,\text{ms}$ (call this Q).