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Al Tobias (wat4y) - Office: Gibson S123 & Physics 218, (434) 924-0538

Physics Demo Manual

Demonstrations are cataloged according to PIRA Bibliography


Due to Physics Building renovations, the lead time to set up demo requests has increased due to the need to transport equipment across campus. Please be kind and let me know well ahead of time what you need.

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 Harmonic Motion
  video  - Transverse Waves
  video  - Longitudinal Waves
 Acoustic levitation
  video  - Standing Waves
 Soap Film Standing Waves
 Bell in a Vacuum
  video  - Doppler Buzzer
  video  - Diffraction & Interference in Ripple Tank
 Double Slit Interference of Microwaves
 Interference of Sound Waves
  video  - Tuning Fork Beats
  video  - Oscillator Beats

Double Slit Interference of Microwaves


To demonstrate the double slit diffraction / interference pattern of microwaves.


PASCO Manual on Double Slit Interference of Microwaves.

UVA Physics Lab 10 Manual on Light and Microwave Interference.

Set up the microwave transmitter/source and receiver/detector as shown in the image. Orientation of each should be such that the horn width in the horizontal plane is greater than the horn height in the vertical plane (rotation angle reads 0-degrees). Also note the source label and detector readout both will face upward. This gives us vertically polarized microwaves.

Place the generator on the main arm of the goniometer such that the hood lies directly over the goniometer’s center point (hinge). Place the receiver on the goniometer’s shorter arm so that the horns are about 25 cm apart.

Cover the transmitter's horn with the metal double slit plate and connect the receiver output to the LED bar indicator. The receiver amplifier should be set to x1 (most sensitive).

Sliding the receiver about the goniometer's axis will indicate the main maximum at 0-degrees and the first order minima and maxima at 40-degrees.


The original E805867 Demo Lab receiver/detector does not work with this demo, use an elementary lab one with the green paint on it.

The LED bar can be replaced by a digital voltmeter.