Motor with battery pack on a fishing swivel
Motor with battery pack on a fishing swivel

 

Code Number: 3B22.10

Demo Title: Standing Waves in a String - Hanging Motor

Condition: Excellent

Principle: Standing Waves on a String.

Area of Study: Oscillations & Acoustics

Equipment: 

Motor with battery pack on a fishing swivel, bright colored string.

Procedure:

Start the motor and let it hang from the end of the string.  Adjust the length of the string until standing waves are visible.  Up to seven nodes should be obtainable. 

NOTE:  The motor must be balanced around the center of mass for this to work well.

References:

  • Imelda S. Caleon, R. Subramaniam, "Exploring Students' Conceptualization of the Propagation of Periodic Waves", TPT, Vol. 48, # 1, January 2010, p. 55.
  • Alison Hapka, "Handheld Standing-Wave Generator", TPT, Vol. 38, #6, Sept. 2000, p. 342.
  • W-122, "DC Motor on String", DICK and RAE Demo Notebook.
  • Don Rathjen, Paul Doherty, "String Machine", Square Wheels, 2002, p. 119.
  • Borislaw Bilash II, David Maiullo, "Standing Wave Generator", A Demo a Day: A Year of Physics Demonstrations, p. 210.
  • Arbor Scientific, "Simple, Inexpensive Standing Wave Kits Get The Entire Class in on The Act", p. 2.
  • Chris Chiaverina, "Inexpensive Standing Wave Apparatus", The Newsletter of the Wisconsin Association of Physics Teachers, Number 8, March 1999.