Graphs of Transverse Waves
- There are two common graphs transverse waves;
- Displacement against distance
- Displacement against time
- These are:
- Similar because they produce a sinusoidal shaped curve
- Different because displacement against distance is showing displacement of a point on the wave, but displacement against time is showing the wave itself moving along a line
- On the displacement-distance graph:
- Movement upwards from the centre line is given a positive sign and movement downwards a negative
- The amplitude and wavelength can be found as shown below
- On the displacement-time graph:
- The time period can be taken directly as shown
- This means that frequency can be found indirectly as f = 1/T
- To determine the next position of a point on the wave
- Sketch the full wave after time has passed by looking at the direction of travel
- Each point oscillates perpendicular to the wave, so remains on the normal line wherever the wave intersects, this is shown in red below
Graphs of Longitudinal Waves
- Plotting displacement against distance also produces a sinusoidal shaped graph
- This can be used to show where the compressions and rarefactions will be found
The graph shows how the displacement of a particle in a wave varies with time.Which statement is correct?
A. The wave has an amplitude of 2 cm and could be either transverse or longitudinal.
B. The wave has an amplitude of 2 cm and has a time period of 6 s.
C. The wave has an amplitude of 4 cm and has a time period of 4 s.
D. The wave has an amplitude of 4 cm and must be transverse.