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Table of ContentsBrownian Motion -- a small chamber is filled with smoke and observed with a Brownian video camera and projection TV. Brownian motion of the smoke particles is observed.
Brownian Motion Simulator -- a small variable speed motor shakes a four-sided frame mounted over a glass plate on the overhead projector. Small metal balls and a larger plastic disc are placed in the frame, and when the vibrator is turned on the motion of the balls (atoms) striking the disc (smoke particle) knock it randomly about.
Equipartition of Energy -- equal division of kinetic energy among gas molecules is simulated using different mass balls in the molecular motion simulator. Larger balls travel more slowly than small balls.
Crystal Lattice Models -- ball and stick models of various crystal lattices.
Plasma Tube -- an evacuated tube containing a metal conductor is energized by a Tesla coil and forms long flickering streamers of current which are attracted to fingers touching the outside of the tube.
Franck-Hertz Effect -- classic experiment demonstrating quantized energy levels of bound electrons. A voltage/current curve for a discharge through a noble gas is displayed on the oscilloscope and seen to contain repetitive peaks and valleys.
Bohr Atom (hydrogen spectrum) -- the spectrum from a hydrogen arc is seen by the class using pass-out transmission gratings, one for each student.
Lattice Energy Level Model -- soft foam “egg carton” material simulates energy levels in a regular atomic lattice.
Line Spectra -- hydrogen, neon, mercury, and helium emission tubes are examined with transmission gratings which are handed out to the students. The sources are arranged in a vertical stack and operate simultaneously, so that all four spectra are seen at once. A white light atop the stack may be turned on separately to compare a continuous spectrum with the four quantized emission spectra.
Absorption by Sodium Vapor -- a salt-soaked stainless steel screen is held in a flame in front of two backlit screens; one lit by white light and the other by sodium light. In front of the white light screen, the flame is transparent and faintly yellow. In front of the yellow sodium light screen, the flame appears black.
Neophan Glass -- a sheet of neophan glass interposed into a continuous spectrum demonstrates absorption lines.
Radiation Spectrum of Hot Objects -- light from a slide projector powered by a Variac is spread into a spectrum. With the Variac at a low setting the projector bulb is red-hot and the spectrum consists of red light only. Turn the Variac up slowly, and as the temperature of the bulb increases the spectrum comes to include orange, yellow, green, and (at white heat) blue light.
Bichsel Boxes -- two 3x5 index card boxes each with a small hole in the lid; one is painted black inside and the other white. Hold the boxes up to the students with the holes facing them and they appear almost identical. Open the lids and the difference is obvious. Useful in discussing blackbody cavity radiation.
Blackbody Radiator -- a small metal cube has a narrow hole drilled in the side. As viewed with a video camera, the hole appears darker than the surrounding metal. If the cube is heated with a blowtorch to a high enough temperature, the hole will glow brighter than the surrounding metal.
Leslie Cube -- a brass cube filled with hot water has four different faces: one is plain brass, one painted white, one painted glossy black, and one painted flat black. A thermocouple connected to a projection galvanometer is positioned near the Leslie cube and the cube is rotated on its base so that each face passes in front of the thermocouple. A different rate of radiation is seen from each face.
Discharge Tube and Pump -- electric current runs through a glass tube as it is being evacuated. The glow from the current goes from nothing at atmospheric pressure to a maximum at low pressure and finally back to nothing when the tube is fully evacuated. At the proper pressure level, a structured discharge is seen.
Millikan Oil Drop -- recreation of the classic experiment used to find the ratio of electron charge to mass. Must be individually viewed by the students during class changeover.
Millikan Oil Drop Analog -- aluminized ping-pong balls bounce back and forth between two oppositely-charged metal plates, exchanging charge.
Thomson's E/M Experiment -- an electron beam in an open oscilloscope is deflected by an electric field, then by a transverse magnetic field which balances the electric field and reduces the deflection to zero. Ratio of electron charge to mass could then be calculated from the values for deflection and field intensities, but this demo is usually only done qualitatively.
Superconductor -- modern ceramic superconductor levitates a small rare-earth magnet (viewed on projection TV) at liquid nitrogen temperatures.
Film Loops:
- Brownian Motion and Random Walk
- Avogadro's Principle
- Graham's Law (Diffusion)
- Absorption Spectra
Michelson Interferometer -- classic interferometer demonstrates interference of two beams of coherent light. Mirrors may be moved to shift fringes.
Streib's Relativity Machine -- a device which simulates length and time contraction at relativistic speeds.
Length Contraction -- show and tell item with boards of different lengths to display the length contraction at 0, .9c, .99c, .999c, etc.
Film Loops:
- The Speed of Projectiles, Sound, and Light
- Simultaneity is Relative
- The Michelson-Morley Experiment
- Relativistic Ride
Single Slit (variable width) -- a variable-width single slit shows diffraction of a laser beam.
Cornell Slides (single, double, and multiple slits) -- a slide containing single slits of different widths, double slits of different separations, and multiple slits with various numbers of slits per centimeter.
Aperture (Airy disk) -- projected circular diffraction pattern from passing a laser beam through a small aperture.
Knife Edge -- a projected edge diffraction pattern using a razor blade, laser, and lens.
Arago's Bright Spot -- bright spot in the center of the shadow of a small sphere. Can be individually viewed at class change or projected from a video camera.
Point and Eye of Needle -- Individually viewed diffraction pattern of light around and through eye and point of a needle.
Hair or Thin Wire -- projected diffraction pattern from a thin wire in a laser beam.
Barrier Penetration -- microwaves are beamed into a large plastic prism, and are totally internally reflected off to the side. (the detector shows no microwaves penetrating straight through). When another prism is slid up against the first to make a square, the microwaves suddenly penetrate straight through both prisms even though there is still a tiny air gap between the two.
Bragg Scattering of Microwaves -- microwaves are beamed into a model “atomic lattice” consisting of regularly-spaced metallic balls. Interference fringes are observed in the reflected beam as the detector is swung around.
Electron Diffraction -- electrons from a hot filament are diffracted by a thin slice of graphite to produce a circular interference pattern. The size of the rings can be changed by altering the accelerating voltage (and thus the wavelength) of the electrons.
Photoelectric Effect (Electroscope) -- bright light from an arc lamp strikes a metal plate mounted atop a negatively charged electroscope. Scope discharges quickly if the plate is zinc, less quickly for aluminum or copper. Will not discharge if a plate of glass is held between the light and the zinc (cuts out UV), or if the electroscope is positively charged.
Electron Discharge Tube with Wheel -- a small paddlewheel is free to roll along the axis of an electron discharge tube. When current is flowing through the tube, electrons strike the paddles and transfer momentum to the wheel, rolling it along the tube. Reverse the current and the wheel rolls the other way; shows that electrons have momentum.
Electron Discharge Tube with Cross -- electrons fly through a discharge tube and cause a phosphor screen at the end of the tube to glow. Raise a metal cross into the path of the electrons and a cross-shaped shadow appears on the screen, showing that electrons travel in straight lines.
Millikan Oil Drop -- recreation of the classic experiment used to find the ratio of electron charge to mass. Must be individually viewed by the students during class changeover.
Millikan Oil Drop Analog -- aluminized ping-pong balls bounce back and forth between two oppositely-charged metal plates, exchanging charge.
Thomson's E/M Experiment -- an electron beam in an open oscilloscope is deflected by an electric field, then by a transverse magnetic field which balances the electric field and reduces the deflection to zero. Ratio of electron charge to mass could then be calculated from the values for deflection and field intensities, but this demo is usually only done qualitatively.
Software:
SCHROD -- solution of SchrÖdinger equation for various potentials, using the Numerov method. The potential and the initial wave packet energy can be varied by the user.
WAVPAK -- time-evolution of a gaussian wave packet running into barrier, well, and SHO potentials. Values of potential and wave packet energy can be varied by the user.
Franck-Hertz Effect -- classic experiment demonstrating quantized energy levels of bound electrons.
Bohr Atom (hydrogen spectrum) -- the spectrum from a hydrogen arc is seen by the class using pass-out transmission gratings, one for each student.
Line Spectra -- hydrogen, neon, mercury, and helium emission tubes are examined with transmission gratings which are handed out to the students. The sources are arranged in a vertical stack and operate simultaneously, so that all four spectra are seen at once. A white light atop the stack may be turned on separately to compare a continuous spectrum with the four quantized emission spectra.
Absorption -- salt-saturated asbestos is held in a flame and backlighted by a sodium lamp behind a translucent screen. The edge of the flame appears dark due to absorption of the sodium light by sodium in the flame. Change the backlight to ordinary white light and the dark fringe disappears.
Neophan Glass -- a sheet of neophan glass interposed into a continuous spectrum demonstrates absorption lines.
Radiation Spectrum of Hot Objects -- light from a slide projector powered by a Variac is spread into a spectrum. With the Variac at a low setting the projector bulb is red-hot and the spectrum consists of red light only. Turn the Variac up slowly, and as the temperature of the bulb increases the spectrum comes to include orange, yellow, green, and (at white heat) blue light.
Luminescence -- a luminescent rubber ball, skeleton etc. which may be charged up by normal (or UV) light for a glow-in-the-dark effect.
Shadow Sheet -- a luminscent sheet that can be charged up by the from a camera flash unit. Put your hand in the way of the flash and a “shadow” of your hand will appear on the sheet. Also has a small “pen” light source that can be used to write (temporarily) on the sheet.
Chemiluminescence -- one of those chemical light sticks. Break the vial inside and as the two chemicals mix they emit a green glow.
Millikan Oil Drop -- recreation of the classic experiment used to find the ratio of electron charge to mass. Must be individually viewed by the students during class changeover.
Millikan Oil Drop Analog -- aluminized ping-pong balls bounce back and forth between two oppositely-charged metal plates, exchanging charge.
Thomson's E/M Experiment -- an electron beam in an open oscilloscope is deflected by an electric field, then by a transverse magnetic field which balances the electric field and reduces the deflection to zero. Ratio of electron charge to mass could then be calculated from the values for deflection and field intensities, but this demo is usually only done qualitatively.
Film Loops:
- Scattering in One Dimension (Barriers)
- Particle in a Box
- Scattering in One Dimension (Square Wells)
- Free Wave Packets
- Scattering in One Dimension (Edge Effects)
- Absorption Spectra
- Scattering in One Dimension (Momentum Space)
Software:
QUANPOT -- display of the bound states of different potentials, which include a simple harmonic oscillator, a square well, a hydrogen-like atom, and others.
LEGEND -- plots a Legendre polynomial of any order up to 100. Scale dimensions can be varied to examine small details closely.
Ionization -- X-rays discharge a charged electroscope at a distance.
Absorption -- interpose a lead sheet between the X-ray source and the electroscope and the electroscope discharges more slowly.
Sample X-ray Tubes -- various commercial tubes.
Crystal Lattice Models -- ball and stick models of various crystal lattices.
Cloud Chamber -- an automatically-cycling Wilson cloud chamber shows the tracks of alpha particles.
Rutherford Scattering -- an analogue of Rutherford's classic alpha scattering experiment has rolling ball bearings which strike a “nucleus” and scatter at various angles.
Geiger Counter -- commercial Geiger counter detects beta and gamma rays. Both artificial and natural radioactive sources are available. Probe and source can be put in a special frame which allows the distance between them to be varied to determine the effect on count rates. Absorbers of different materials fit in slots in the frame to demonstrate their effect on intensity.
Half-Life -- a computer-based Geiger counter is used to demonstrate the half-life of a short-lived isotope. A chemical extraction process is used to isolate an isotope of protactinium with a half-life of about 100 seconds (the isotope is a daughter product of a much longer-lived isotope). The Geiger counter measures the count rate of the beta decay for the protactinium and displays it in graph form as count rate vs. time. The rapid decay of the isotope can easily be seen and a rough calculation of the half-life can be done.
Nuclear Magnetic Resonance -- nuclei of atoms in an intense magnetic field absorb radio-frequency energy at their resonant frequency; shows as a “blip” on the voltage in a small pickup coil.
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