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Code Number: 3B33.20
Demo Title: Group and Phase Velocity
Condition: Good
Principle: Group & Phase Velocity
Area of Study: Oscillations & Acoustics
Equipment:
Overhead transparencies with ratios of 9:10.
Procedure:
Superimpose the two sheets on an overhead projector. Moving one sheet against the other will give you a group velocity that is different than the velocity of the sheet that is moving.
A simple way to do this demonstration is to take two combs and pass one in front of the other to show the group and phase velocity.
References:
- Carl E. Mungan, "Using Desmos to Understand the Difference Between Phase and Group Velocity", TPT, Vol. 59, #1, Jan. 2021, p. 30.
- V. Van Deynse, "A Simple Device to Demonstrate Phase and Group Velocity", TPT, Vol. 22, # 3, Mar. 1984, p. 166.
- John Coenraads, "Phase and Group Velocity", TPT, Vol. 11, # 1, Jan. 1973, p. 36.
- Erik Stijns, "Simple Demonstration Showing the Difference Between Group and Phase Velocity", AJP, Vol. 52, #8, Aug. 1984, p. 755.
- M. Paul Hagelberg, "Phase and Group Velocity Demonstration", AJP, Vol. 46, # 5, May 1978, p. 579.
- C. Dean, "Simple Demonstration of the Concept of Group Velocity", AJP, Vol. 41, #11, Nov. 1973, p. 1282.
- Frank S. Crawford, "Water-Wave Machine for Demonstrating Group Velocity", AJP, Vol. 41, #10, Oct. 1973, p. 1203.
- J. Mawdsley, "Letter Re: 'Demonstrating Phase Velocity and Group Velocity'", AJP, Vol. 38, #4, Apr. 1970, p. 547.
- J. Mawdsley, "Demonstrating Phase Velocity and Group Velocity", AJP, Vol. 37, #8, Aug. 1969, p. 842.
- Robert Katz, "Group-Phase Velocity Demonstrator", AJP, Vol. 21, #5, April 1953, p. 388.