Oscillations and Waves
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3A10.10 |
OSCILLATIONS |
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Pendula |
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Simple Pendulum |
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The length of the pendulum is adjustable. A timer can be used to measure the period. |
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3A15.10 |
OSCILLATIONS |
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Physical Pendulum Set |
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Physical Pendulum |
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Hang the pegboard on the nail from some random hole. Hang weights from support hole and mark its path using the chalk. Repeat with different holes until an intersection of lines is achieved. Mark this spot as the center of mass. |
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3A20.10 |
OSCILLATIONS |
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Springs and Oscillators |
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Mass on a Spring |
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Set up equipment as shown and place a hooked mass on the spring. Pull down and release to start simple harmonic motion. If desired, time the oscillation and calculate the frequency. Change to a different mass in order to change the frequency. |
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3A40.10 |
OSCILLATIONS |
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Simple Harmonic Motion |
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Circular Motion vs. Mass on a Spring |
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Shadow project a ball at the edge of a disc rotating at the same frequency as a mass on a spring. |
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3A60.10 |
OSCILLATIONS |
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Driven Mechanical Resonance |
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The "dead dog" version runs ten minutes on video disk. The film loop runs 4:40. The entire film can be purchased from 8 sec clips can be found online at |
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3A70.20 |
OSCILLATIONS |
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Coupled Oscillations |
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Coupled Pendula |
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Two pendula hang from a flexible metal frame. Start one pendulum oscillating. The pendula will pass the energy back and forth. A third pendulum can be added. |
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3B10.10 |
WAVE MOTION |
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Transverse Pulses and Waves |
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Pulse on a Rope |
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Disc 09-09 |
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A long rope runs the length of the lecture bench or between two people. One end is held steady. Jerk the other end of the rope up and down to create a pulse. Vary the tension to vary the speed of the pulse. |
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3B10.30 |
WAV MOTION |
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Transverse Pulses and Waves |
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Shive /
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Disc 09-12 |
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Thin rods are mounted on a fine wire that twists easily. Displace the rod at one end to create a torsion pulse or wave. The other end can the left free to move, fixed in place, or critically damped. |
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3B20.10 |
WAVE MOTION |
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Longitudinal Pulses and Waves |
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Hanging Slinky |
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Disc 09-15 |
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A long slinky is suspended along a frame. Stretch and compress the spring quickly to create a pulse or wave. A spot can be attached to the spring to show that the wave travels and the medium only oscillates. |
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3B22.10 |
WAVE MOTION |
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Standing Waves |
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Melde's Apparatus |
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Disc 09-27, 09-28 |
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A string is help under tensions and driven by a variable frequency oscillator. Changing the frequency will change the number of modes. A strobe can be used to see the waves. |
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3B40.10 |
WAVE MOTION |
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Doppler Effect |
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Doppler Buzzer |
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Disc 10-21 |
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A buzzer and battery are tied to the end of a long string. Start the buzzer and whirl it in a horizontal circle over your head. Point out the differences in sounds between the moving and stationary buzzer. |
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3B50.40 |
WAVE MOTION |
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Interference and Diffraction |
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Moiré Pattern Transparencies |
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Disc 09-23 |
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Pairs of identical transparencies have circular wave patterns of different wavelengths. Place transparencies on the overheard projector. Vary their relative positions to produce different interference patterns. |
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3B55.10 |
WAVE MOTION |
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Interference of Sound |
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Speaker Bar |
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Disc 10-20 |
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A variable function generator drives two speakers which are mounted on the ends of a long bar. Set the frequency to about 3kHz. The speaker bar is on a turntable. Direct the students to plug one ear and listen for the variations in intensity while you slowly turn the turntable. Alternately, have the students move their heads back and forth while plugging one ear (the speakers do not move). Inclusion of a rheostat allows one speaker to be turned off. |
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3B55.40 |
WAVE MOTION |
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Interference of Sound |
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Trombone |
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A function generator drives a speaker. The sound travels through two tubes which joining together at the horn. One tube is a trombone slide. Change the distance the sound travels in the sliding tube by raising or lowering the slide. The variation in intensity as the slide is moved is quite pronounced at 3kHz. Measure the change in length of the sliding tube (twice the distance moved). |
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3B60.10 |
WAVE MOTION |
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Beats |
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Beat Forks |
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Strike the tuning forks with the rubber mallet and observe the beats on the oscilloscope. Vary the beat frequency by adjusting the position of the small masses on the one tuning fork. Decrease the time scale to look the wave form within the envelope. |
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3B60.20 |
WAVE MOTION |
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Beats |
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Beats on Scope |
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Disc 10-19 |
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Two nearly equal signals are the input into an oscilloscope using tuning forks or two function generators and a speaker. Compare the oscilloscope to what you hear. Decrease the time scale to look at the individual waves within the envelope. Vary the beat frequency and look at the changes. |
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3C20.10 |
ACOUSTICS |
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Pitch |
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Hook a function generator to a speaker. Change the pitch as the class listens. Have the class raise their hands only as long as they can hear at the extreme ends of the hearing range. At subsonic frequencies you can see the speakers vibrate. Hearing -3dB is often shown at the same time. |
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3D30.70 |
INTRUMENTS |
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Resonance in Cavities |
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Hoot Tubes |
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Disc 11-07 |
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Long tubes that have screen wire near one end are held over a burner. Heat until the screen is hot. The tube sounds when removed from the flame when held vertically, but stops when held horizontally. |
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3D40.20 |
INTRUMENTS |
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Resonance in Plates, Bars, and Solids |
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Singing Rod |
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Disc 10-08 |
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A long aluminum rod will sing when it is stroked along its length with rosin and supported at its center. Find the center by balancing the rod on your finger. Rub some rosin on your free hand and vigorously stroke the rod. You will need to squeeze hard. Also try holding the rod at a point 1/3 or 1/4 of its length to excite higher harmonics. |
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3D40.30 |
INTRUMENTS |
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Resonance in Plates, Bars, and Solids |
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Chladni Plate |
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Disc 09-30 |
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A square plate is clamped at its center. Sand is sprinkled on it and the place is excited with a bow. The sand will show the nodal lines of the excited pattern. The pattern will change depending on where you bow on the edge. Alternatively, the plate can be excited using a mechanical vibrator and a frequency generator as shown. |
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