3B22.10 Vibrating String
A string is driven by a function generator that is attached to an oscillator. By adjusting the frequency of the oscillation, the string can be used to demonstrate standing waves. A strobe light is used to see the motion of each mode. Note: practice this demo in advance, knowing the frequency of each mode is essential.
-  Function generator
-  Mechanical oscillator
-  BNC-banana cable
-  Lab stand
-  Aluminum bar
-  90-degree clamp
-  Roll of string
-  Strobe light
-  Foam
- Place the lab stands about 70 cm apart, clamp an aluminum bar to fix the distance between two lab stands.
- Mount an oscillator on one lab stand.
- Attach one end of the string to the oscillator and the other end to a 90-degree clamp mounted on the other lab stand.
- Connect the oscillator to a function generator.
- Turn on the function generator and adjust the string tension until desired effect is obtained.
- Place the strobe light below the string.
- Use the foam to block direct light from the strobe.
- The use of strobe lights may induce seizure in people with epilepsy or photosensitivity, give students advance notice of the use of such lighting
- Turn on the function generator and adjust its frequency.
- Turn off the room light.
- Turn on the strobe.
- Change the frequency as necessary.
- PIRA 3B22.10
- Don't attempt this at home!
If you have any questions about the demos or notes you would like to add to this page, contact Ricky Chu at ricky_chu AT sfu DOT ca.