7A50.40 - Bohr Model - Vibrating Circular Wire
Clamp the mechanical vibrator body to the Bohr atom board. Use a pair of pliers to then clamp the vibrator wire to the middle of the nearest rubber band. It will be necessary to attach new size 32 rubber bands before use. Approximate frequencies are:
N=1 - 31.75 Hz.
N=2 - 41.4 Hz.
N=3 - 55.6 Hz.
N=4 - 68.5 Hz.
To enhance the viewing of the vibrations, position the blacklights above the vibrating apparatus. The string has been painted with some green fluorescent paint and will show up quite nicely in a darkened room.
When set up, the Pasco wire loop apparatus gives preferred modes of oscillation that are not even integer wavelengths. This makes it necessary to pin the loop at a position 180 degrees from the oscillation points. 1, 2, and 3, wavelengths are then easily seen. Approximate generator frequencies for the wavelengths should be:
1 wavelength = 22 Hz.
2 wavelengths = 65 Hz.
3 wavelengths = 134 Hz.
4 wavelengths = 228 Hz.
The Pasco wire loop is very stiff and will not show vibrations above 3 wavelengths very well. Higher wavelengths can be made more visible by making a wire loop from softer wire.
- Peter Riggs, "Revisiting Standing Waves on a Circular Path", TPT, Vol. 59, #2, Feb. 2021, p. 100.
- Erlend H. Graf, "Rubber Band Bohr Wave Functions", TPT, Vol. 62, #5, May 2009, p. 310.
- Danning Bloom and Dan W. Bloom, "Vibrating Wire Loop and the Bohr Model", TPT, Vol. 41, #5, May 2003, p. 292.
- Michael J. Bernstein, "Waves from the Lumberyard", TPT, Vol. 12, #6, Sept. 1974, p. 366, reprinted Vol. 41, #6, Sept. 2003, p. 369.
- Y. K. Vijay, "Mechanical Oscillations in a Circular Loop", AJP, Vol. 64, #8, Aug. 1996, p. 1077.
- L. W. Casperson and M-A. Nicolet, "Vibrations of a Circular Membrane", AJP, Vol. 36, #8, Aug. 1968, p. 669.
- H. F. Meiners, "Standing Waves in a Circle", AJP, Vol. 33, #10, Oct. 1965, p. xiv, also Apparatus Notes, July 1965-December 1972, p. 8.
- "S-105: Standing Electron Waves Demonstration", DICK and RAE Physics Demo Notebook.
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