Demonstration Catalog

Demonstrations

A. Classical Mechanics
I. Measurement
II. Kinematics
III. Forces
IV. Energy
V. Center of Mass and Torque
VI. Linear Momentum and Impulse
VII. Angular Momentum

B. Fluids
I. Fluid Statics
II. Fluids Dynamics

C. Heat and Thermodynamics
I. Heat
II. Thermal Radiation

D. Electricity and Magnetism
I. Electric Charge
II. Capacitors and Dielectrics
III. Magnetism
IV. Circuits
V. Electromagnetic Oscillations

E. Sound
F. Waves
G. Light and Optics
H. Atomic Physics

Catalog of Physics Lecture Demonstrations and Props

Department of Physics, Oregon State University, 301 Weniger Hall Corvallis, OR 97331-6507 Contact Jim Ketter at (541) 737-1712 or email at ketterj_at_physics.oregonstate.edu


A. Classical Mechanics
I. Measurement
	1. meter stick, ruler, tape measure, quart, pint, liter, clock, stopwatch, etc...
	2. (Light cardboard) Cubic centimeter, cubic decimeter (1 liter)
	3. Masses, mass sets, weights, spring scales, balances, etc...
	4. 30 cm long stick that indicates the distance light travels in 1 nanosecond (in a vacuum)
	5. 22.4 liter (cardboard) cube. Represents volume of 1 mole of ideal gas at STP
	6. Metal disk with one radian indicated. Arc length is marked by piece of tubing that can be removed to show that length of arc equals radius.
	7. Coordinate system unit vectors. Wooden rods in blocks representing various coordinate systems. Can show components of 3-D vector.
	8. 4'x4' dry-erase board, perfect for drawing graphs. Large white board has 1 inch grid etched into surface for ease in drawing large graphs or for any other purpose where a grid is needed.

II. Kinematics
	1. Constant velocity. Air car with metronome (amplified). Marks made along track at each tic will be equally spaced. Can be done with lab dynamics cart and 2 meter track as well.
	2. Constant acceleration. Wheel rolls down inclined plane marked with increasing distance intervals. Metronome (in sync with marked distance intervals) shows that each increasing distance interval is passed in equal time intervals. Distances can be graphed versus time.
	3. Constant acceleration, qualitative. Any dropped ball/object. Air car on air track with string over pulley with accelerating mass. Cart on table with string over pulley with accelerating mass.
	4. Gravitational Acceleration - feather versus ball. Feather and ball enclosed in clear tube fall at different rates in air but fall together when tube is evacuated w/ vacuum pump. Alternative: paper versus crumbled ball of paper.
	5. Gravitational acceleration, direct measurement. Time of fall of an object is measured directly and gravitational acceleration is computed.
	6. Two dimensional motion, fall is independent of horizontal velocity. One ball is launched horizontally while another is dropped vertically. Both balls hit floor at same time based mostly from sound of balls hitting floor. Only students up front may be able to see this happen.
	7. Two dimensional motion, monkey and hunter. Projectile is fired at falling object and strikes object no matter the muzzle speed or angle.
	8. Two dimensional motion, water jet parabola. Show angle of maximum trajectory, parabolic path, etc... Currently not available.
	9. Assortment of balls. Golf, basketball, volleyball, tennis, ping-pong (plus paddles), steel, acrylic, marbles, plastic, lead, super, "happy and sad", bowling, billiards?, wooden, etc... For pendulums, projectiles, collisions, etc....

III. Forces
	1. Inertia. A mass with two strings is hung from one string. If the lower string is jerked, it will break; if the lower string is pulled slowly, the upper string breaks.
	2. Inertia. Card is pulled out from under bottle. Index card is flicked out from under quarter balanced on thumb. Table cloth is pulled out from under dishes.
	3. F=ma. Acceleration of air car (or rolling cart) measured for given accelerating mass (falling, on string over pulley.) Force, mass or both can be varied.
	4. Static Equilibrium, Vector nature of Force. Combination of masses on strings over pulleys reach equilibrium. Forces and components are measured and calculated. Angles can be knowns or computed unknowns.
	5. Hooke's Law. Spring w/ weights shows F is proportional to x.
	6. Frictional Force. Friction block w/ various surfaces. Frictional force can be measured for the various materials; coefficient of friction can be calculated.
	7. Centripetal Force. String w/ rotating weight. Similar set-up to common lab experiment. Calculations possible with timed rotations.
	8. Centripetal Force. Various. Flattened hoop, governor, centrifuge, liquid in container, wine glass with liquid on platform swung around in vertical circle. Bucket of water swung around upside down. Rotating chair/platform.
	9. Centripetal Force w/ calculation. Conical pendulum; force computed from angle of rotating weight.
	10. Centripetal Force measured directly. Scale and mass on rolling car are put on rotating table. Centripetal force is read from scale.
	11. Resonance. a) Driven mass on spring shows resonance when driving frequency equals mass/spring resonant frequency. b) Pendulums of different lengths (hanging from same support) shows that a swinging pendulum can only cause one of same length to also start to swing.

IV. Energy
	1. Kinetic Energy, 1/2 mv^2. A mass hung from string over pulley accelerates air car (or rolling cart.)
	2. Conservation of Energy, Bowling ball Pendulum. Pendulum released from in front of nose returns to same position. Likelihood of flinching is inversely proportional to trust in science.
	3. Energy wells, equilibrium. Roller Coaster Roller coaster shaped track has potential wells of different depths. Ball started with enough potential energy can get from one well to next. Also, shows stable and metastable equilibrium points.
	4. Conservation of Energy, Loop the loop. Ball on loop d loop track makes the loop if started w/ enough potential energy.
	5. Conservation of Energy. Pendulum. Pendulum wraps around obstructing peg if potential is high enough and peg is low enough.
	6. Conservation of Energy. Pile driver. Falling mass drives nail. PE to KE to work on nail.

V. Center of Mass and Torque
	1. Center of Mass isn't in center (necessarily.) Two wooden cylinders of equal mass but different size are joined and balanced. Balance point is not where cylinders are joined.
	2. Center of Mass Determination. Irregular object and plumb bob, hung from various suspension points. Plumb bob string always passes through center of mass.
	3. Cone Rolling Uphill. Double cone rolls to high end of two sloping rails, paradoxically rolling uphill. Center of mass is actually lowering.
	4. Motion of Center of Mass.Irregular object thrown rotates about its center of mass.
	5. Motion of Center of Mass. Two air cars oscillate about connected spring. Flag at center of mass shows motion of center of mass to be uniform (when oscillating cars are hidden. (Qualitative).
	6. Motion of Center of Mass. Irregular object on air table moves such that center of mass follows a straight line.
	7. Static Equilibrium, Vector nature of Force including Torques. Combination of masses on strings over pulleys reach equilibrium on "L" shaped bar. Forces and components and torques are measured and calculated.
	8. Teetor Totter. Different masses can be hung at different positions; resulting torques can be calculated and shown to be in equilibrium.
	9. Balanced Meter Stick including Center of Mass. Meter stick is balanced with masses at different positions; center of mass of meter stick must be included to equilize torques.

VI. Linear Momentum and Impulse
	1. Conservation of Momentum: Four balls hanging from strings. (Newton's Cradle.) Quantized momentum wave appears to pass down row of balls. A "loaded" version is also available for descrepant event demo.
	2. Conservation of Momentum: Air Car Collisions. Several possible variations: a) elastic collisions without timer/clock: 1M into 1M, 1M into 3M b) elastive collisions with timer: 1 M into 1 M, 2 M or 3 M. c) inelastic collisions with timer
	3. Conservation of Momentum: Internal Forces . Two air carts react through released spring. Momentum is conserved.
	4. Forces act on center of mass.Irregular object accelerated with tangential force on air table; center of mass accelerates parallel to applied force as object rotates and translates across table.
	5. Rocket Propulsion. Water rocket, fan on air car (or rolling cart), fire extinguisher powered human cart.
	6. Internal Forces. Fan on air car blows onto a plate also mounted on car. As long as momentum changes are internal, car won't move.
	7. Impulse/Momentum Theorem: Cushioning the Blow. Raw egg thrown into suspended blanket cannot be broken, even if thrown very hard. The cushioning of the blanket extends the time, reducing the force required to stop the egg.
	8. Momentum Transfer. Drop a super ball atop a larger ball (basketball for example) and the superball will bounce amazingly high when the two hit the ground and the larger ball's upperward momentum is transferred to the smaller ball in the collision w/ the ground.

VII. Angular Momentum
	1. Moment of Inertia Disks. Cylinders, hoops, disks, rolled down inclined plane and times are compared (qualitatively). Can run as a series of "races" keeping track of winners and losers. Result (should be): All similarly shaped objects (no matter size or mass) will roll in same time. (All solid spheres tie with all solid spheres, etc...) Larger inertia shapes (hoops) will always lose.
	2. Moment of Inertia Wheel. Falling weight (on string wrapped around hub) accelerates wheel w/ variable moment of inertia.
	3. Conservation of Angular Momentum. Ball rotating at end of string; when string is shortened, ball rotates faster.
	4. Conservation of Angular Momentum on Rotating Platform (chair). a) Student volunteer changes angular velocity of platform by extending or contracting hand-held weights. b) Bicycle wheel with angular momentum is rotated and imparts angular momentum to platform.
	5. Change in Angular Momentum Produces Torque. Counterweight produces torque on gyroscope which cause gyroscope to precess which creates a torque that prevents gyroscope from toppling over.
	6. Gyroscope - Precession and Nutation. Air bearing gyro shows complicated motion that results from torques acting on system and energy conservation.
	7. Flippy Tops. Small top flips over and spins on "top" when spun fast enough.

B. Fluids
I. Fluid Statics
	1. Pressure, Constant Level Tubes. Interconnected tubes show that fluids seek a constant level, no matter the shape/volume of tube. Can deduce pressure increases w/ depth and is determined from depth, not volume. Good one to ask for student guess as to which tube will fill highest before releasing liquid and showing them.
	2. Pressure: U-Tube with different density fluids. Shows pressure is proportional to density. Can be used to calculate specific gravity of the lighter fluid (oil.)
	3. Pressure/Force. A cap on the end of a tube placed in water remains until water poured into the tube reaches the level of the water that the tube is placed in.
	4. Pressure, Mariotte's Bottle. Air tube in sealed bottle allows one to vary the pressure with respect to an exit.
	5. Pascal's Law. Hydraulic Lift. Small weight on small piston lifts large weight on large piston.
	6. Archimedes' Principle. Objects are lowered into vessel of water on balance. Weight of water decreases by weight of water displaced. Weight required to restore balance is equal to weight of displaced water. This can also be done in a shortened form.
	7. Buoyancy, Variable Density. Cartesian diver and density ball show that flotation depends on relative density differences.
	8. Buoyancy of air. Objects of different volume that are balanced at atmospheric density are unbalanced when air density is decreased (in vacuum bell jar).
	9. Weight of Air; Barometer. One side of a mercury manometer is evacuated. Height difference of column reaches 76 cm and no more.
	10. Hydrostatic Paradox. Glass tube is hung by scale in a vessel of water. Pressure in glass tube is decreased and water rises into tube. If this water is held up by air pressure, why does the scale show an increase in weight?.
	11. Air Pressure can exert Large Force. a) break a ruler/wooden slat under a sheet of newspaper. b) Magdeburg spheres. c) Collapsing metal can (ditto fluid!) after boiling small amount of water inside, then capping and allow to cool. Can collapse is gradual but impressive. d) Almost same as "c" but with soda/beer can. Boil small amount of water in can, then invert very quickly into cool water. Can collapse is dramatic.
	12. Air Pressure, quickies. a) Index card over mouth of drinking glass filled with water stays in place, even when inverted. b) "Magic" bottle full of water doesn't empty when inverted but pencils (other small objects) can be inserted up into the water. c) Student in large plastic trash bad, closed around neck or waist, vacuum (cleaner) hose inserted in opening removes air (quickly) and "vacuum packs" the student. d) Peeled, hardboiled egg is sucked into jar but can't be pushed in from outside.
I. Fluid Dynamics
	1. Venturi Tube. Diameter of a tube varies and a pressure difference arises for fluid (air) passing through the tube as evident from columns of fluid (manometers).
	2. Bernoulli Effect Demos. a) Ball is support in a column of air or held in an inverted funnel by virtue of Bernoulli Effect. b) Blowing between two suspended ping-pong balls causes balls to moved closer together (not separate.) c) Blowing over a floppy sheet of paper causes floppy end to rise.
	3. Sky Hook. A cap on the end of a tube placed in water remains until water poured into the tube reaches the level of the water that the tube is placed in.
	4. Bernoulli Effect, An Interesting Sailboat. When an air stream is blown past a rotating cylinder, the cylinder experiences a net force and moves.
	5. Viscosity. Bubbles move up tubes at different velocities when the tubes are filled with oils of different viscosities.

C. Heat and Thermodynamics
I. Heat
	1. Gas Thermometer. Constant volume and/or constant pressure gas thermometer can be used to illustrate temperature or change of state of gas (external work is performed in constant pressure process but not in constant volume process).
	2. Thermal Expansion of Metals. a) A metal sphere passes through a heated loop. b) a heated bimetal strip bends when heated. c) a heated rod breaks a shear pin as it cools.
	3. Heat and Energy. Rotating tube is held by nutcracker brake. Friction heats tube and pops cork.
	4. Thermal Conductivity. Match heads light or was pellets melt and drop as heat travels down metal rods.
	5. Specific heat of metals. Samples of hot metal melt ice and the specific heat is determined by the amount of water melted. (Similar to lab where temperature of water is raised by hot metal.)
	6. Effect of Pressure on Boiling Point. Warm water boils when pressure is reduced with aspirator.
	7. Boiling Point, Pulse Glass. Fluid boils from the heat of hand at one end of tube and condenses at the other end of tube.
	8. Anomolous Expansion of Water. Projected capillary tube shows contraction then expansion of water as temperature rises about 0 degrees C. Takes about 10 minutes.
	9. Freezing by Evaporation; Triple Point of Water. Cryophorus or high capacity pump reduces pressure sufficiently that water will evaporate or boil until it is cool enough to freeze.
	10. Phase Transition of Naphthalene. Computer data logger shows that temperature is constant across the freezing-melting transition.
	11. External Work Performed by Heat. Rubber band warmed with heat gun will lift 1 kg a distance of about 4 cm. High enough to be visible in lecture hall.
	12. Heat from Mechanical Energy. a) Two steel balls held in each hand are quickly smashed together with a sheet of paper held between the two. Energy is large enough to scorch/burn the paper (which can be seen and smelled.) b) Rubbing hands together warms them.
	13. Reversible Processes, Entropy. Viscous fluid and laminar flow allow one to (apparently) thoroughly mix a drop of dye into a fluid, and then unmix the drop.
	14. Molecular Vibration Tube. Colored glass particles supported by turbulent mercury vapor in a heated tube model the random motions of atoms in a gas.
	15. Kinetic Theory Model. Agitated plastic beads model the random motions of atoms in a gas. Image of beads is projected on wall. Shows velocity is proportional to temperature.
	16. Adiabatic Expansion. Ball bouncing on air cushion or the rewarming of air that has been adiabatically decompressed allows one to calculate gamma.
	17. Filling, Emptying Problem. 5" to 6" water pressure applied to jug. Pressure is released and air in jug does work pushing excess air out. This is an adiabatic process and the air left in the jug cools down. Measurement of final pressure let's one measure gamma.
	18. Imploding beer can. Fill can w/ steam and quickly immerse in cold water. Can implodes impressively.
	19. Adiabatic Ignition under Pressure. Plunger tube has small piece of cotton in bottom. Plunger is rapidly, forcefully compressed, igniting the cotton in a small flash. (Cannot be repeated quickly; wastes need to be cleaned out of narrow tube.)
II. Thermal Radiation
	1. Surface Emissivity. Heated cube (heated with hot water from tap) has faces that emit different amounts of radiation which can be detected with a thermopile or pulse glass.
	2. Electromagnetic Nature of Thermal Radiation. a) Heating coil is focused by mirror onto temperature sensitive card and produces a rough image. b) Heating coil focused by mirror onto matchhead ignites match.
	3. Blackbody Radiation. Container is heated and emits radiation through hole in side.
	4. A Hole as a Blackbody. Hole in black box is "blacker" than any paint or fabric...
	5. Blackbody versus Reflective Body. A black painted can and a silver can each containing water and a thermometer, exposed to a heat lamp will show the black can heats up more quickly to higher temperature.

D. Electricity and Magnetism
I. Electric Charge
	1. Historical Electrostatic Demos. Cloths, rods, electroscopes, and various paraphenalia show that two kinds of charge exist and that they exert forces on themselves and each other.
	2. Gee Whiz Charged Rod (Induced Charge). An 8 foot long 2x4 balanced on an overturned watch glass can be moved by the presence of a charged rubber or acrylic rod. Similarly, an emtpy pop can can be rolled across the table...
	3. Cathode Ray Tube. Various discharge tubes show that charges can carry kinetic energy to move a paddle wheel or heat a piece of foil and that they tend to move in straight lines casting shadows.
	4. Wimshurst Machine, Van de Graaf Machine. Generate large, static voltages and create impressive discharging (sparks). Make hair of doll or volunteer stand on end with van de Graaf. Used to drive demos below.
	5. Kinetic Demos using Electrostatic Forces. a) A (conductive) ping pong ball suspend from string bounces between two charged plates. b) A dipole shaped rotor and discharge points (on two charged plates) will rotate making an electrostatic motor. c) Electrostatic discharges will turn a pinwheel or power chimes.
	6. Electrophorous, Electrostatic Induction. Metal plate in close proximity to plastic sheet on which charge resides can be charged repeatedly by induction. (Similar to lab where temperature of water is raised by hot metal.)
	7. Fields inside and outside a charged conductor. Pith balls outside a charged cylinder will be repelled from each other while pith balls inside the charged cylinder experience no forces.
	8. Charge on Outside of Conductor; Faraday Cage. A plastic cup filled with packing (styrofoam) peanuts sat atop the van de Graaf makes an impressive "peanut" fountain when machine is turned on. Same peanuts in metal can on top of van de Graaf don't fly out. Good discrepent event - ask students their opinion of the metal cup following the plastic cup - they almost always say the metal cup will have the peanuts fly out more/faster/higher.
	9. Faraday ice pail experiment. Demonstrates electrostatic induction and shows that charges reside on the exterior surface of a conductor.
	10. Faraday Cage. a) Metal cage lowered over radio blocks signal from getting to radio. b) Dipole antenna transmitter and receiver can have signal block by metal cage over receiver. c) See #8 above.
	11. Mapping an Electric Field. Powdered felt follows along the electric field lines produced by a set of (hi voltage) electrodes in different orientations. Done on the overhead projector so that the image of the field lines is projected onto the screen.
II. Capacitors and Dielectrics
	1. Parallel Plate Capacitor w/ and w/o Dielectric. Electroscope shows change in potential when the distance between the two capacitor plates is changed or when a dielectric is placed between the plates.
	2. Force on Dielectric. Air car supports dielectric which is attracted into the space between two charged, parallel capacitor plates.
	3. Dissectable Leyden Jar. Leyden jar is charged, then dissembled. Upon reassembly, jar is shown to still be charged. Charge must reside on the dielectric (insulator.)
	4. Displacement Current. Capacitor is connected to battery through a galvanometer and current is observed to flow. Current also flows if plate separation is changed.
	5. Energy Stored in a Capacitor. Capacitor is charged to 300 V and then the leads of the capacitor are touched together creating a spark and a loud snapping sound. (This is why they put "danger" labels on electronic devices, even for when they are turned off and unplugged.)
III. Magnetism
	1. Magnets, various. Bar magnets, horseshoe magnets, electromagnets, lodestone, refridgerator magnets, etc...
	2. Magnetic Force on Electric Charge. Electron beam in cathode ray tube is deflected by a magnet.
	3. Magnetic Forces, Magnetic Mirror, e/m Ratio. Electron beam tube between Helmholtz coils allows one to show the magnetic force, determine the e/m ratio, or, using a bar magnet to produce a diverging B field, reflection in a magnetic field (magnetic mirror). This is difficult/impossible to see in a large class.
	4. B is a Vector Quantity. Compass needle points in the direction resulting from the superposition of two B fields produced from two coils whose currents can be varied.
	5. Mapping a Magnetic Field. a) Image of iron filings on a glass plate in the presence of a magnetic field is projected onto a screen via overhead projector. b) Small (transparent) compasses align with magnetic field, projected onto screen via overhead projector. Note: These can be done with bar or horseshoe magnets, a single, current-carrying wire, or the coiled wires of a solenoid.
	6. Forces Between Current-Carrying Conductors. Current is passed through suspended wires and their motion is observed. Right (left) hand rule demonstrated.
	7. Force on Current-Carrying Wire in Magnetic Field. Current is passed through suspended wire within the field of a horseshoe magnet and the motion of the wire is observed. Right (left) hand rule demonstrated.
	8. Torque on Current Loop in Magnetic Field. Current loop forms magnetic dipole which aligns with the external magnetic field.
	9. Current Balance. Quantitatively measures the force between current-carrying conductors. Not visible in large class.
	10. Faraday's Law. Flux through loop is changed with a permanent magnet and/or an electromagnet and the induce current is shown on a galvanometer.
	11. Homopolar Motor and Generator. A disk rotated through the poles of a magnet produces a voltage between its center and edge. If current is passed through a similar disk, it will rotate.
	12. Eddy Currents; Lenz's Law, Magnetic Braking. a) Solid conductive disk rotated between the poles of a magnet is dramatically slowed while similar though slotted disk rotates (more) freely. b) Air track car is dramatically slowed when it travels through the poles of a magnet. c) Jumping ring: An aluminum ring is supported in the field of an a.c. magnetic coil. If the magnet is pulsed, the ring jumps. A split ring will not exhibit the same behavior. Supercooling (in liquid nitrogen) the rings will make the resulting jumping much more dramatic.
	13. Inductance, Energy Stored in an Inductor. Current is run through an inductor and a large arc occurs if the circuit is interupted.
	14. Magnetic Properties of Materials. Paramagnetic and diamagnetic behavior is seen when samples of various materials are held between the poles of a magnet.
	15. Curie Temperature. Low curie point material (lighter flint) made into a pendulum loses its attraction to a magnet when it is heated to its curie temperature. Result is slow oscillation.
	16. Barkhausen Effect. The alignment of magnetic domains in a magnetic field may be heard when picked up on a sensing coil and amplified.
	17. Hysteresis. Display on oscilloscope for several materials.
IV. Circuits
	1. Kirchoff's Law. Voltages and currents are measured in a simple DC circuit and their values are compared to calculations.
	2. Wheatstone Bridge. Allows measurement of an unknown resistance or voltage.
	3. Negative temperature coefficient of resistance. The voltage and current of a carbon filament lamp are measured for various values of current and the resistances are calculated.
	4. RL, RC Circuits. (Large classroom) Scope shows the exponential relation between voltage and time when circuit is made or interupted.
	5. LCR Resonance. When circuit is powered by a signal generator, a scope shows the changes in reactances as resonance is reached. Circuit rings when hit by a pulse. See mechanical analogs under "Forces", "Waves" or "Sound".
V. Electromagnetic Oscillations
	1. Tesla Coil. a) Large, dramatic display - Coil provides high frequency electromagnetic field that causes electrical breakdown and discharge in air, glow tubes, etc... Big, loud and scary. b) Small, handheld Tesla coil provides sparks up to an inch in length. Hot enough to scorch paper.
	2. Resonant Leyden Charge Ciruit. Tuned spark gap excites voltage in similar, parallel circuit.
	3. Dipole Radiation / Antennas. Radiation from excited dipole is picked up by second dipole. Shows polarization. Faraday cage available to shield second antenna.
	4. Lecher wires, transmission lines. R.F. signal sets up standing waves on parallel wire transmission line that can be terminated in various ways.

E. Sound

	1. Sound Makers. Tuning forks (with or without resonant chambers), organ pipes, recorder, stretched strings, slotted spinning disk with air blown across holes, plastic ruler, wine glasses, heated "sound" tubes, etc...
	2. Sound requires a medium for transmission. Sound from a ringing bell inside bell jar ceases as the chamber containing the bell is evacuated via vacuum pump. Glowing light bulb inside same bell jar is still visible whether evacuated or not.
	3. Standing Waves, Resonance. Length of cylinder is varied by letting water flow in or out. A struck tuning fork is placed at the open end of the cylinder and when the length of the hollow tube is correct, resonance occurs and the sound intensity increases.
	4. Harmonics. Magnets place along the vibrating string of a sonometer produce signals which shows that several frequencies are being excited at the same time.
	5. Beats. Beat frequencies can be heard from two tuning forks of slight different frequency or from two audio oscillators.
	6. Young's Double Slit/Constructive and Destructive Interference. Two speakers powered by a common source produce an interference pattern throughout the room similar to that from light going through a double slit. Sources can be pivoted about so that the interference pattern of high and low intensity (volume) can be swept across the audience; students can hear the nodal and antinodal points move past them. With sources fixed, all students who are in a nodal point (for example) can raise their hands, showing the nodal lines radiate out through the room.
	7. Doppler Shift. Small oscillating speaker on a wire is swung overhead and its pitch can be heard to vary as the speaker alternately approaches and recedes from the observer.
	8. Coupling. Threads tied to a wire coat hanger (or fork, or wrench, or...) are wrapped around the observers index fingers which are then placed in the observers ears. When the hanger is struck, it makes a pleasant/interesting "gong" sound for the observer but this sound, which couples poorly to the air, isn't heard by others. Can be passed around to students
	9. Echoes/Reverberations. Sound of two boards clapped together is seen on an oscilloscope - the original clap followed by the reverberations can be discerned.

F. Waves

	1. Relation of Simple Harmonic Motion to Circular Motion (Reference Circle). The shadow of a pointer on a spinning turntable is projected onto a screen (or wall) together with the image of a mass on a spring oscillating with the same amplitude and period. With some care, they can be seen to move together.
	2. Wave Motion Generator. Slinkies, ropes, springs allow one to transmit pulses down lines and observe reflections.
	3. Longitudinal and Transverse Waves. Hand-cranked wave model shows waves that are longitudinal, transverse, or a combination of the two.
	4. Standing Waves, Superpositioning. Projection model shows how the superposition of traveling waves can result in standing waves.
	5. Standing Waves in Rope. A rope is excited with a variable frequency generator and standing waves occur at resonant and higher harmonic frequencies.
	6. Coupled Harmonic Motion. Two pendulums that are coupled by a spring exchange energy and show beating effects.
	7. Combinations of Harmonic Motion - Lissajou Figures. a) Sine waves are put into the horizontal and vertical input of an oscilloscope and combine to produce circles, lines, "daisy" figures, and more complicated patterns. b) Sand pendulum swinging in two dimensions leaves a path of spilt sand in Lissajou patterns.
	8. Resonance - Driven Harmonic Oscillator. Mass and spring system is driven with variable frequencies which includes the resonant frequency.

G. Light and Optics

	1. Reflection and Refraction. a) Shown with large prism and mirrors with light source on lens board. b) Laser beam projected into tank of water can be seen to "bend" at interface. Can be reflected off mirror or water surface. Beam can be seen in air via chalk dust blown into path.
	2. Total Internal Reflection. a) Tank of water and light beams at various angles show total internal reflection. b) Large prism on lens board with light source.
	3. Lenses. Large lens board with light rays show basic principles of lenses and ray tracing.
	4. Real Images - The Phantom Light Bulb. Real image of light bulb appears superimposed with real lamp socket but then disappears.
	5. Model of the Eye. a) Spherical fluid-filled cavity plus correcting lens focuses images on back of cavity. b) Small, model of eye with various lenses, focuses image on back panel of model. c) Antique cross-section view of eyeball with "rays" (of metal rod). Perhaps more interesting than instructive.
	6. Polarization. Polaroid sheets for the overhead and/or to pass around the room. Can show polarization by reflection, scattering, calcite crystals, polaroid material. Can show applications such as stress analysis (stress in plastic), LCD's (such as on calculator or laptop), etc...
	7. Corner Reflector. Three mutually-perpendicular mirrors (forming a corner) send light rays back parallel to their incoming direction (independent of orientation) (Used in bicycle and automotive reflectors, for example).
	8. Interference Model. Overhead transparencies with circular wave fronts show two source interference.
	9. Interference - Young's Double Slit. Laser projects double slit interference pattern on wall/screen. Slit separation is variable.
	10. Thin Film Interference - Soap Bubbles and Newton's Rings. Reflection image of soap film or Newton's rings is projected on wall/screen to show colored bands produced by interference.
	11. Single Slit Diffraction/Interference. a) Students observe interference pattern through slit created by their own fingers (or finger/thumb). b) Laser projected through single slit onto wall/screen shows interference pattern.
	12. Diffraction Gratings - Continuous and Line Spectra. Grating breaks white or Hg light into components that are projected onto wall/screen. Different gratings may be used; multiple orders can be seen.

H. Atomic Physics

	1. Crystalline Models. Various models showing different symmetries.
	2. Photoelectric Effect. Hg light will discharge a negatively charged electroscope but not a positively charged one. A glass plate (opaque to U.V.) will stop the discharge.
	3. Sodium Resonance. Tube with sodium vapor is transparent to white light but absorbs and reradiates light from a sodium lamp.
	4. Cloud Chamber. Paths of various subatomic particles can be seen in the cloud chamber. This is not visible from far away (not for large classrooms) but perhaps can be projected with an opaque projector (found in large lecture hall.)
	5. Piezoelectric Effect. Crystals can serve as microphone or loud speaker, or voltage can be measured when pressure is applied.
	6. Nuclear Magnetic Resonance. Shows up as a scope trace.
	7. Geiger Tube, Air. Tube is evacuated until proper pressure is reached.
	8. Stopping Power, Qualitative. Speaker hooked to geiger counter lets one hear counts from radioactive source. Putting various materials between source and detector gives a qualitative estimate for how penetrating different sources are.