Category Archives: Wave Motion

Two – Wave Interference Model

Demo: OW-B-WI
Pira Index: 3B 50.55

 Lab Equipment  Directions
  1.  foamboard superimposed waves
  1.  With the two waves folded flat against each other, slide red waves past white waves, stopping when waves are lined up to show complete constructive interference. Slide waves farther along to a point representing complete destructive interference.


Wave Demo

Demo: OW-B-WD
Pira Index: 3B 10.50

 Lab Equipment  Directions
  1.  sinewave model demonstrator
  1.  Move the lower black wave board back and forth to show constructive and destructive interference.
  2. A second wave board can be substituted to demonstrate a wave pattern with both different amplitude and frequency.


Vibrating Bars

Demo: OW-B-VB
Pira Index: 3B 60.10

 Lab Equipment  Directions
  1.  tone bars – (3 bars)
  2. tuning fork mallet
  1.  Using the mallet, strike a bar marked 440, then the bar marked 441. You will hear 1 beat/sec.
  2. Stop the vibration of both tone bars. Set the two 440 bars side by side. Strike one of the 440 bars, then quickly lay your hand on it to stop its vibration. You will hear the sympathetic vibration of the 440 bar.


Traveling Wave Machine

Demo: OW-B-TW

 Lab Equipment  Directions
  1.  traveling wave apparatus
  2. overhead projector
  1.  Put the wave apparatus on the overhead and focus onto the screen.
  2. Set the wave in motion and observe the motion on the screen.
  3. Point out the dot of hot glue on one loop of the apparatus. Does it move forward with the wave motion?

Turntable Resonance

Demo: OW-B-TR
Pira Index: 3B 70.00

 Lab Equipment  Directions
  1.  Pendulum bob and string
  2. lab stand
  3. pendulum clamp
  4. turntable
The pendulum length is measured from the center of the ball to the clamp.
Adjust the length of the string to the turntable so that it just long enough to not pull loose as it rounds the far side.
  1.  A 44cm long pendulum is attached to a lab stand. A second string is attached to pendulum string, just below the support. The other end of this second string is attached to the edge of a record turntable.
  2. If the turntable is set to 33 1/3 (or 78) the pendulum shows disorganized motion.
  3. At 45rpm it starts to swing in response to its natural frequency.


Standing Waves in a Wire

Demo: OW-B-SW
Pira Index: 3B 22.10

 Lab Equipment  Directions
  1.  IEC F-41 frequency generator
  2. pulley with table clamp
  3. telescope
  4. short rod
  5. 2 wires with different diameters
  6. slotted weight set
  7. weight hanger
  8. adaptor, DB-f to BNC-m
  9. magnet
  10. 2 BA leads, 2 BB leads
  11. Pasco mechanical vibrator
  12. string adaptor for vibrator
  1.  Set up as shown in figure A or figure B.
  2. Both setups use 1-8, figure A uses 9-10; B uses 10-12.
  3. Adjust frequency to obtain various standing wave patterns.
  4. Add weights to hanger and observe the change of the wave patterns.


Speed of Sound

Demo: OW-B-SS
Pira Index: 3B 30.00

 Lab Equipment  Directions
  1.  Pasco function generator
  2. Speaker (Auratone) with phono DB adaptor
  3. oscilloscope (T 912)
  4. microphone
  5. cardboard tube ~1.5m (red striped)
  6. adaptors: BNC-f to DB-m, BNC-f to BNC-f
  7. leads: 2 BNC-DB, BNC-BNC
  8. lab stand
  9. ring holder
  10. parallel clamp
  11. meter stick
  1.  Connect the equipment as shown.
  2. Place the speaker face up on the floor and hold the cardboard tube over it.
  3. Hang the microphone down into the tube and observe the flattened first section of the wave pattern.
  4. As the microphone is raised or lowered, changing the distance sound travels to reach it, the length of the flattened wave section changes correspondingly.


Standing Waves – Pasco Cord

Demo: OW-B-SP
Pira Index: 3B 22.10

 Lab Equipment  Directions
  1.  Pasco function generator
  2. two BB leads (long)
  3. two long lab poles
  4. two telescope clamps
  5. strobe light
  6. 500g hooked mass
  7. two long rods, 1 short
  8. two bungee cords
  9. five 90 degree clamps
  10. mechanical vibrator and string adaptor
  11. pulley
  12. long yellow wire
  1.  Set up equipment as shown.
  2. Adjust frequency to obtain various standing wave patterns listed.
  3. This set up will show from 1-7 nodes using 500 grams on the weight hanger and 10 to 90Hz on the function generator.
Center to center measurements:
short pole to string adaptor = 10cm
short pole to pulley = 107cm
2 antinodes when frequency = 20Hz
3 antinodes when frequency = 30Hz
4 antinodes when frequency = 40Hz