| TAP 320 - 2: Phase difference and superposition
This question helps you check your understanding of phase difference and gives you further practice in superposing waves.
Graphs of waves
A graph of wave displacement against position shows a wave 'frozen' in space at an instant of time. Really, the waves are travelling along. The graph shows 'snapshots' of two waves, A and B.
1. What is the phase difference between A and B? Give your answers in fractions of a wavelength and degrees. There are at least two correct answers to this question!
2. Sketch the superposition pattern of A and B.
The next diagram shows two more waves, C and D.
3. What is the phase difference between C and D?
4. Sketch the superposition pattern of C and D.
5. What phase angle corresponds to a phase difference of 1/3 of a wavelength?
6. Sketch a diagram showing two waves of equal amplitude with a phase difference equal to 1/3 of a wavelength.
A suitable question to support demonstrations of superposition, phase and path difference.
Answers and worked solutions
1. Zero phase difference
3. One oscillation (or wavelength for a displacement amplitude graph) is equivalent to 360º. Therefore:
This activity is taken from Advancing Physics chapter 6, 10W