Whistling Whirly Tubes

 

whirly tube

  • Hold handle-side of tube securely and twirl around rapidly in a circle. Tube makes a whistling sound that can be heard long distances, resulting from standing pressure waves that set up in the tube. Pitch of whistle depends on twirling speed, however, because only standing waves produce a whistle, the pitch of the whistle goes from one octave to the next in discrete jumps. See: sound pipe document for further explanation.
  • Can also use tube to demonstrate Bernoulli’s principle. Pressure difference between tube ends results from faster motion of outer end. Pressure differential produces air flow through tube. Stationary end of tube (handle end) acts as a vacuum and will suck up small pieces of paper when outer end is twirling.
  • Located in L02, section C2.

Polarization (outreach set)

polarization

Demos in this set include:

  • Planar light source with large polarizing sheet
  • Corn syrup
  • Long spring
  • Plastic fork
  • Wafers of micah and benzoic acid crystals
  • Cubes of calcite, selenite, and Iceland spar
  • Disappearing cube
  • Polarizer model (looks like a gate), with light model (wavy wire piece)
  • Square and circular polarizers

Beats Demo

beats3

beats2

beats1

  • Listen to beat frequencies through speakers, while simultaneously seeing waves with oscilloscope. Use scope’s math function to add waves together. Resultant wave (shown in red, above) displays beats.
  • Demo consists of 2 function generators, 2 speakers, and one
    oscilloscope.
  • Located in L02, section C2; Oscilloscope located in L35,
    section F4

 

Driven Oscillator

 

Driven Oscillator Demo Picture

When the sine wave generator is tuned to the right freequency ( the natural frequency of the mass-spring system) the mass oscillates with very large amplitude. When generator is not tuned to the natural frequency of the spring (even if off by .1 Hz), oscillation amplitude is very small.

Location

  • Pasco Sine Wave Generator and Driver: L35, section C3
  • Masses: L35, section D1
  • Ring Stand: L35, section A
  • Spring: L35, section C2