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  • C4-61: ACCELERATION ON A SCALE

    C4-61
    Illustrate forces in an accelerating system.
    A rigid frame hangs from a spring scale as photographed. In the frame, a mass hangs from a spring. The mass is pulled down and attached to a hook at the bottom of the frame by a short thread loop. (Ask your students how this affects the weight shown by the spring scale.) In this position the spring scale reads about 8 Newtons. Q: When the string is burned, releasing the mass, will the reading on the spring scale immediately after the string breaks (a) increase, (b) decrease, or (c) stay the same? A: It will increase, as seen on the accompanying mpeg video. The last photograph shows details of the lower connection of the weight to the hook.

  • D2-51: BICYCLE WHEEL PENDULUM

    D2-51
    Demonstrate the Parallel Axis Theorem.
    A bicycle wheel is suspended at its axis on a physical pendulum, as seen in the photograph above. Set it swinging, and invite students to predict how its motion will change if the wheel is given some initial rotation versus with it initially not rotating versus with it fixed and unable to rotate (cord for fixing wheel available upon request).

    This demonstration can be used to introduce the Parallel Axis Theorem.

  • D3-06: ROTATING CHAIR - HELICOPTER MODEL

    D3-06
    Demonstrate conservation of angular momentum.

    Rotation of the large weighted propeller by a person sitting in the rotating chair causes rotation of the chair in the direction opposite to the direction the propeller is rotated, as demonstrated very effectively by Gwen in the photographs above.

    d3-06d3-06b

  • E2-71: MILLISECOND PULSAR

    E2-71
    To "hear" the signal from a pulsar.
    This audio tape cassette contains the signal from a pulsar converted to audio frequencies.

    Note: requires large audio cart to play in lecture halls.
    E2, FS1

  • E2-72: AUDIOTAPE 14 MIN - NRAO PULSAR

    e2-72
    To listen to a pulsar
    This audio cassette tape contains 14 minutes of pulsar signals converted to audio. Obtained through the NRAO.

    Note: requires large audio cart in lecture halls.
    E2

  • G1-16: PENDULUM WITH LARGE OSCILLATION

    G1-16
    Show the difference between pendula with small amplitude and large amplitude of oscillation, and to show rotational motion where the kinetic energy at the top is much less than the change of potential energy from the top to the bottom of the oscillation.
    The Oberbeck Cross is used with three of the weights at their minimum and one at its maximum radius. The motion of the pendulum for various amplitudes, including complete rotation, can be simply observed or can be compared with computer simulations of the 360 degree pendulum. Because of the large change of potential energy, the velocity of the bob changes significantly when it is given just enough energy to undergo full circular oscillations.

  • G1-58: LOADED PENDULUM

    G1-58
    Analog to the longitudinal motion of a particle in a particle accelerator driven by a sinusoidal accelerating potential.
    The position of the pendulum bob, displaced from the vertical by the hanging weights, represents the phase of a particle being accelerated in a particle accelerator. The sinusoidal accelerating voltage creates oscillations of the particle about its equilibrium phase. The phase of the accelerating particle oscillates about the equilibrium phase, as does the pendulum.

  • G1-74: LISSAJOUS FIGURES - LASER AND LOUDSPEAKER

    G1-74
    Show Lissajous figures created by music to form a laser show.
    A front-surface mirror is suspended in front of the center of a large loudspeaker in an orthogonal suspension. A laser beam bounces off the mirror onto a nearby white screen, creating varying Lissajous patterns as the music plays. This suspension encourages the mirror to move with two basically orthogonal oscillations, combining to form Lissajous figures, as seen above.
    OS5

  • G2-02: FORCED HARMONIC MOTION WITH DAMPING - LARGE

    G2-02
    Demonstrate and graph driven and damped harmonic motion.
    Variable speed motor can be run below, at, or above the resonant frequency of a mass hanging on the spring. Two masses are provided. Inserting a felt-tipped pen into the holder and starting the paper rolling allows you to graph the motion of the oscillating mass.

    Note that this has been largely replaced by G2-09.

  • G2-04: DAMPED OSCILLATIONS

    G2-04
    Demonstrate damped harmonic oscillations.
    Pull down or lift up the aluminum mass on the end of the spring and release to obtain oscillations. Moving the magnet so that the aluminum bar moves in the magnet gap creates very strong eddy current damping. By inserting a pen into the holder and scrolling the paper roll with the motorized drive, a graph of damped harmonic oscillation can be drawn.

    See G2-09 for the updated version of this demonstration.

  • H1-23: SPEED OF SOUND IN ALUMINUM

    H1-23
    Compare the measured and the theoretical values of the speed of sound in aluminum.
    An aluminum rod is stroked (See Demonstration H3-71: STROKED ALUMINUM ROD.), setting up longitudinal standing waves in the rod. The frequency f is determined using a frequency meter, with or without the aid of an audio oscillator. The length L of the rod, one-half wavelength for the fundamental, is measured using a two-meter rule. The speed of sound in aluminum is then S = 2fL. The theoretical value is obtained by using the Young's modulus Y and the mass density d: S = SQRT(Y/d), where the Young's modulus Y=7.0x10^+10 Pa and density of aluminum d=2.699x10^+3 kg/m^3. Putting in numbers, S = SQRT(Y/d) = 5,093 m/s. For the first mode of the stroked rod, the wavelength is twice the length of the rod, so measuring the length of the rod L = 1.83m, and the frequency of the first mode f = 1370 Hz, the speed of sound in aluminum is S = 2fL = 5,014 m/s.

  • H3-15: TWIRL-A-TUNE AND VACUUM CLEANER

    H3-15
    Demonstrate standing wave resonances in an open tube.
    To produce resonant frequencies of the tube, hold the end with the cork up to the input of the vacuum cleaner. As you cover the vacuum input more and more with the cork, more air will be pulled through the Twirl-a-Tune, exciting higher harmonics. Up to around 16 harmonics can be obtained.

    Note that this demonstration is very loud, and should not be used for very long or in a small, enclosed space. For smaller classes or for extended analysis and discussion, consider other demonstrations from this section.
    OS1

  • H4-51: MODULATION - AM AND FM

    H4-51
    Demonstrate AM and FM signal modulation as an introduction to vibrato and tremolo.
    The Pasco Dual Function Generator is used to produce either amplitude modulation or frequency modulation using various combinations of sine, triangular, and square waves. Frequency modulation is pure vibrato and amplitude modulation is pure tremolo; actual vocal vibrato is a combination of pure vibrato and pure tremolo.
    H4, ME2

    h4-51ah4-51b

  • H4-55: YAMAHA DX7S DIGITAL SYNTHESIZER

    H4-55
    Demonstrate features of a modern digital synthesizer.
    This device is a modern digital synthesizer. An enormous number of functions and effects can be illustrated using this instrument. Please see Demonstration Reference File for manuals on its operation and features.
    OS5, ME3

  • H4-92: AUDIO RECORDING - DIGITAL DOMAIN DEMONSTRATION CD

    H4-92
    Examples of early digital sound reproduction.
    Compact disc with audio system.

  • H4-95: AUDIOTAPE - NONESUCH GUIDE TO ELECTRONIC MUSIC

    H4-95
    Early recording of various electronic music effects.
    Audiotape with audio system.

  • H5-15: EFFECT OF HARMONIC CONTENT ON TONE QUALITY

    H5-15
    Illustrate Ohm's Law of Hearing, and to hear the sounds of complex waves produced by the Fourier Synthesizer.
    A Fourier Synthesizer including 12 harmonics with independently adjustable amplitudes and phases is connected to an oscilloscope and loudspeaker. Several relevant demonstrations can be performed using this setup: (1) Produce various wave shapes. Listen to the difference in sound as each harmonic is added while the wave is being synthesized. Compare the sounds of the different wave shapes. (2) Demonstrate that although the wave shape changes when the phase of any of the harmonics is changed, change of phase of harmonics has a negligible effect on the timbre or tone quality. Ohm's Law of Hearing states that the sound of a complex tone is to a great degree independent of the phases of the harmonics. (3) Remove the fundamental from a complex tone - best for the pulse train, which has large-amplitude harmonics. The frequency of the fundamental is still audible due to difference tones created by the non-linear mechanism of the ear. The frequency of a complex wave is due in large part to the combined effect of all of the harmonics, illustrating the "missing fundamental."(4) Demonstrate fundamental tracking by varying the frequency of the synthesizer with the fundamental missing. The ear follows the missing fundamental frequency.
    H5, ME2, ME3

  • H5-17: WAVETEKS AND AUDIO CART - QUALITY BEATS

    H5-17
    Demonstrate second order or quality beats.
    One oscillator is set at about 200-500 Hz sine wave, and the other set to the second harmonic (an octave higher) but with about half the amplitude of the fundamental. If the octave is slightly mistuned, the phase of the second harmonic will be continuously changing with respect to that of the fundamental. The slight change in tone quality or timbre is known as "quality beats" or "second order beats." Inasmuch as quality beats are significant, this experiment provides a counterexample to the general statement of Ohm's Law of Hearing.

  • I2-01: CROOKES' RADIOMETER

    I2-01
    Stimulate discussion about radiative heat transfer and conservation of momentum with photons.
    A match or other source of light is brought near the radiometer, resulting in rotation of the vanes. The REAL reason has to do in a very important way with details regarding how molecules interact with each other. The explanation is not nearly as simple as the difference in the momentum of photons when they are absorbed or reflected, or even as simple as the heating effect on the black side, which absorbs more photons, compared with the white side, which reflects more. This appears to be one of those physics devices that is typically explained incorrectly, even in the literature from the supplier that accompanies the radiometer.
    I2

  • I2-03: CROOKE'S RADIOMETER - ROTATION REVERSAL

    I2-03
    Counterintuitive demonstration of Crookes' radiometer designed to make students understand radiation better.
    Heat the Crookes' radiometer with the heater for until it spins very rapidly. When the heater is removed the spinning first ceases then reverses. When the heater is removed, the black side cools faster than the white side. When the temperature of the black side becomes sufficiently below that of the white side the roles are reversed from normal in heating adjacent air, causing more momentum transfer to the white side and rotation in the direction of the black side.
    I2, PS1