| TAP 324- 9: Stationary waves in a string
This is a question about stationary wave patterns set up in a vibrating string.
A vibrating string
An elastic string is clamped at both ends. Near one end a vibration generator is loosely attached. The vibrator oscillates with fixed amplitude but with variable frequency. A graph of maximum amplitude along the string against frequency of vibration is shown.
Sketch the instantaneous appearance of the string at:
4. What is the wavelength of the waves on the string at these frequencies?
5. What is the speed of travel of the waves along the string?
1. 15 Hz is the lowest frequency at which a standing wave is produced. What is the longest wave that can be fitted on the string with a node at each end?
2. 30 Hz will produce a wave of half the length of 15 Hz.
3. 45 Hz will produce a wave of one-third of the length of the 15 Hz wave.
4. You know the length of the string and you know the wavelength in relation to this length.
5. Use v = f .
These questions are closely related to activities concerning standing waves on strings.
Answers and worked solutions
This activity is taken from Advancing Physics chapter 6, 90S