Modern Physics > Quantum Physics DCS# 7A55.xx

PHOTON MOMENTUM



APPARATUS
camera flash unit MK
cymbal 202-06-E
wireless microphone
201A
laptop with spectrum analyzer software and microphone
206


DESCRIPTION
Charge the flash unit, then fire it at the cymbal suspended near the microphones.  A faint ping can be heard.  Use the spectrum analyzer to show that the this is not just the "poof" sound from the flash unit, but a "ping" at the expected frequency of the cymbal.
The "Soundcard Scope" program can be used as a spectrum analyzer.  The graphs below shows the sound of the cymbal struck by hand, and the sound of the cymbal due to the flash.

sound spectrum
          for cymbal struck by hand sound spectrum for flashed
          cymbal

REFERENCES

This site discusses the various mechanisms that could be involved in causing the cymbal to ring:  http://www.millersville.edu/physics/experiments/031/index.php