3C20.23 - Grooves on a Record - LP

Place the LP record onto the turntable.  Place the needle on the 4th track of the E. Powers Biggs record and align the laser to reflect off the mirror and onto the opposite wall of the lecture room.  The vibrations of the needle as it moves over the grooves at constant speed are shown with the large amplitude vibrations giving the largest movements of the laser beam on the wall.
Code Number:
3C20.23
Demo Title:
Grooves on a Record - LP
Condition:
Good
Principle:
Mechanical Vibrations Converted to Sound.
Area of Study:
Acoustics
Equipment:
Turntable with mirror and needle attached to tracking arm, laser.
Procedure:

Place the LP record onto the turntable.  Place the needle on the 4th track of the E. Powers Biggs record and align the laser to reflect off the mirror and onto the opposite wall of the lecture room.  The vibrations of the needle as it moves over the grooves at constant speed are shown with the large amplitude vibrations giving the largest movements of the laser beam on the wall. 

References:
  • Alaina G. Levine, "A Sweet Sound: Physicists Reconstruct Primitive Recordings", March APS News, March 2015, Vol. 24, # 3, p. 3.
  • George M. Hopkins, "A Simple Phonograph", Experimental Science, p. 149.
  • Guinness World Records, "Smallest Functional Vinyl Records", 2003, p. 112.
  • Stan Horaczek, Jon Enoch, "For the Records", Popular Science, Winter 2019, p. 26.

Disclaimer: These demonstrations are provided only for illustrative use by persons affiliated with The University of Iowa and only under the direction of a trained instructor or physicist.  The University of Iowa is not responsible for demonstrations performed by those using their own equipment or who choose to use this reference material for their own purpose.  The demonstrations included here are within the public domain and can be found in materials contained in libraries, bookstores, and through electronic sources.  Performing all or any portion of any of these demonstrations, with or without revisions not depicted here entails inherent risks.  These risks include, without limitation, bodily injury (and possibly death), including risks to health that may be temporary or permanent and that may exacerbate a pre-existing medical condition; and property loss or damage.  Anyone performing any part of these demonstrations, even with revisions, knowingly and voluntarily assumes all risks associated with them.