Match Tuning Forks and Rubber Mallet
Match Tuning Forks and Rubber Mallet

 

Code Number: 3B60.10

Demo Title: Beats - Tuning Fork

Condition: Good

Principle: Constructive & Destructive Interference of Sound Waves

Area of Study: Oscillations & Acoustics

Equipment: 

Match Tuning Forks and Rubber Mallet.

Procedure:

All the tuning forks need to be coated with WD-40 at least 3 times a year to prevent rusting.  To remove rust make a .1 Molar solution of Ammonium Citrate and let the metal parts soak in this for several hours.  Rinse with vigorous scrubbing under running water, dry, and oil immediately.  DO NOT scrape or rub the forks with any abrassive materials as this will change the pitch and vibration of the fork.  Broken boxes need to be reglued with special glues to preserve their resonance properties.

Set the tuning fork side by side and strike.  The beat frequency can be increased or decreased by moving the metal rider on one of the forks.

A piece of clay stuck to one tine of one of the "motor mount" style tuning forks will be enough to be able to hear a slow beat pattern.

References:

  • Panagiotis Lazos, Anastasios Nezis, Nikolaos Kyriazopoulos, "Demonstrating Mechanical Beats on Phosphorescent Foil in Real Time", TPT, Vol. 60, #3, March 2022, p. 207.
  • Jochen Kuhn, Patrik Vogt, and Michael Hirth, "Analyzing the Acoustic Beat with Mobile Devices", TPT, Vol. 52, #4, Apr. 2014, p. 248.
  • Frank J. Blatt, "Beats and Nodes", TPT, Vol. 32, #1, Jan. 1994, p. 5.
  • Thomas B. Greenslade Jr., "Beats Produced by a Moving Tuning Fork", TPT, Vol. 31, #7, Oct. 1993, p. 443.
  • Terrence P. Toepker, "More Beats", TPT, Vol. 29, #9, Dec. 1991, p. 548.
  • R. G. Newburgh, "Lapping in Races as a Model for Beats", TPT, Vol. 28, #8, Nov. 1990, p. 557.
  • H. J. Janssen and E. L. M. Flerackers, "Beats: An Interference Phenomenon", TPT, Vol. 17, #3. Mar. 1979, p. 188.
  • Joe Crnkovich, "More on Partial Credit", TPT, Vol. 16, #2, Feb. 1978, p. 75.
  • W. L. Lama, R. Jodoin, and L. Mandel, "Superradiance in Radiatively Coupled Tuning Forks", AJP, Vol. 40, #1, Jan. 1972, p. 32.
  • "W-355. Tuning Fork - One Time Loaded", DICK and RAE Physics Demo Notebook, 1993.
  • Julien Clinton Sprott, "3.8. Beat Frequencies", Physics Demonstrations, ISBN 0-299-21580-6, p. 163.
  • David Kutliroff, "73. Resonance Demonstrations with Tuning Forks", 101 Classroom Demonstrations and Experiment For Teaching Physics, p. 160.
  • David Kutliroff, "23. Beat Frequency with Tuning Forks", 101 Classroom Demonstrations and Experiments For Physics Teachers, p. 54.
  • Robert Ehrlich, "8.16. Beats Using a Tuning Fork", Why Toast Lands Jelly-Side Down, p. 140.
  • Robert Ehrlich, "K.3. Beats Using Two Sound Sources", Turning the World Inside Out and 174 Other Simple Physics Demonstrations, p. 144 - 145.
  • Joseph Frick, "#149 - Interference of the Sound-Waves", Physical Technics: Or, Practical Instructions for Making Experiments in Physics and the Construction of Physical Apparatus with the Most Limited Means", p. 175.
3B60.10 - Beats - Tuning Forks
3B60.10 - Dr. James Wetzel, PHYS 1611 - Beats - Tuning Forks