tension in muscle

Tension in Arm Muscles

tension in muscle

  • This model can be used to demonstrate the amount of muscle tension required to hold the arm in various positions.
  • The above picture shows that a 1 N weight, held in the hand with the forearm at a 90 degree angle, produces a bicep tension of 12 N.

tension in arm_weight

measuring H

Measuring h with LED

measuring H1

How to measure Planck’s constant using an LED

  • Measure LED threshold voltage using voltmeter and ammeter.
  • LED converts electron energy to photons. Energy lost by electron = energy gained by photon = (electron charge) times (voltage).
  • So, if threshold voltage is 2.2 volts, energy of emitted photon must be 2.2 eV.
  • Use  E=hc/lambda, and measure lambda using Red Tide spectrometer with Logger Pro (see below pic), to determine h. Take data using LEDs of 4 different colors and fit data to line with slope h.
  • Hand held spectrometer can be used to view LED spectrum.

measuring H
measuring H4

measuring H3

measuring H2


Charged Sheet


Use “Fun Fly Stick” to charge up conductive sheet.


Mylar strands align with electric field.


Place support rods together to form cylinder. Electric field of cylinder points outward radially.

  • Located in L01, section A-2

Homopolar Motor



Wire balances on top of battery and is free to rotate. Top of wire touches positive terminal; bottom of wire touches magnet connected to negative terminal. Wire completes circuit and current travels through wire. Direction of magnetic field creates a Lorentz force that causes wire to turn.

Historical significance: First electric motor. First successful model devised by Michael Faraday. See: https://en.wikipedia.org/wiki/Homopolar_motor

  • Located in L01, section B-4.


Sunset Egg




Appearance of egg mimics that of the sky.

Glass egg is translucent, milky white, and contains no pigment- only microscopic particles that scatter light. Short wavelengths of light (blue) have a tendency to scatter off the microscopic particles in the glass; while long wavelengths of light (red and yellow) tend to pass through.  The egg therefore appears yellowish red when held in front of a light source, and blue when held in your hand.

  • Located in L01, section B-6
coulomb force on water1

Coulomb Force on Water

coulomb force on water1

coulomb force on water 2

Charge teflon rod with fake fur (shown in above photo) by rubbing together.

When charged rod is brought into the proximity of water stream, attraction between water and charged rod will cause stream to deflect.

  • Rod and fur located in L01, section A-1.
  • Bucket with hole, and tub, located in L35, section G-3.

Sound and Temperature Pipes

Temperature and Sound

Sound and Temperature Pipes

Copper pipes chime when hit (hang by loop and tap with hard object). Pipes are identical in size and composition, and are therefore identical in pitch.

To see how temperature affects pitch, dip one pipe in liquid nitrogen and cool for 1 minute. Tap both pipes to hear differences in pitch. Caution: DO NOT TOUCH COLD PIPE WITH BARE HANDS. USE CRYO GLOVES. 

Pipes located in L02, section C-1. Ask for assistance with LN2.

weight of air 1

Weight of Air

weight of air 2

Lid of plastic bottle, shown above, is a pump, and can be used to pump air into container.

Place empty bottle on sensitive digital scale and record scale reading. Then pump additional air into bottle and re-weigh.

weight of air 1

  • Bottle and pump located in L02, section B-5.
  • Scale in L35, section D-2.
ein 5

Einstein Illusion


ein 5

Is the mask in the above image concave or convex? Strangely, it appears convex (sticking out towards you) even when viewed from the concave side. Even more strange: the face appears to turn and follow you as you view it from different angles.

ein 2

ein 4

Below is a profile view of the mask.

ein 3

Illusion works best when mask is illuminated from behind.


past light cone 2

Past Light Cone (to Big Bang)

past light cone 2

In a Big Bang universe, the shape of our past light cone is not strictly conical, but tear-drop shaped. The moment of now is located at the pinnacle of the drop, the moment of the Big-Bang is located at the very base.

past light cone 3

To understand why our past light cone has this shape, recall that the distance from a light cone’s surface to its time axis is the photon’s emission distance. All of the photons we see today- from the very early universe- were emitted from regions of space that were, at the time, very close to us. (Spatial expansion caused these regions to separate very rapidly.) So, photons emitted very early in the universe’s history, and photons emitted very recently have small emission distances.

The slope of the light cone represents the recessional velocity of light with respect to our region of space. The fattest part of the light cone corresponds to the moment in time when the photons we are currently seeing, from the Big Bang, first began to approach us.

The model shown above is actually the light cone for a linearly expanding universe (expansion at a constant rate- i.e., recessional velocities do not change with time). The most accurate model for spatial expansion- lambda cdm- is actually very close to this in shape.


Size of Oil Molecule


When droplet of olive oil (oleic acid) is placed on water, oil spreads out until oil layer is 1 molecule high.

If the oil “spill” radius and the size of the original droplet can be measured, one can estimate the length of the oil molecule.

Volume of original droplet = volume of oil spill pancake.

Use wire loop (diameter~1mm), to estimate volume of droplet (assume droplet is wafer, not sphere). Use calipers to measure.


Dip loop in olive oil.


Remove excess oil using paper towel.


Dust surface of water with lycopodium powder. This allows you to see clearly the final diameter of the spill. The larger the container the better.



Dip tip of wire loop into water. Oil immediately spreads out to form circle (very cool to watch!).

Measure diameter with ruler.0329171623

Should get order-of-magnitude accuracy.

  • Lycopodium powder and oil located in L35, corrosive materials cabinet (powder is safe to handle).
  • Tub located in L35.
  • Calipers located in L35, section D-2.
  • Tape measure in L35, section A-1.
friction pen

Friction Pen

friction pen

Heat of friction causes ink in “Frixion” erasable pens to disappear.

Ink reappears when exposed to cold temperatures.

Use lighter for high temp. (Be careful not to burn paper. Just wave flame in front of paper until ink disappears)

Use liquid from compressed air to achieve cold temperatures. (Invert can and spray. Be careful not to get liquid on skin. Extremely cold.)


friction pen2
friction pen 3
friction pen 5

friction pen 6




Leydenfrost Propagation

leydenfrost  leydenfrost2

Heat aluminum blocks to 350 degrees C using adjustable hot plate shown in photo.

Use water dropper (with demo) to place droplets of water onto surface of hot aluminum blocks. Leydenfrost effect causes droplets to hover, and prevents them from evaporating immediately.

Droplets on the ridged block are propelled along the surface- from right to left in above photo.

Raise one edge of the hot plate slightly, so that droplets on smooth surface slide down while droplets on the ridged surface climb up.

See more about this here: http://www.wimp.com/when-water-flows-uphill-the-leidenfrost-effect/




static friction incline

Static Friction Incline

static friction incline


  • Friction prevents the metal washer on incline from slipping. Washer will begin to slide down plane when angle is great enough (one can show that the coefficient of friction is equal to the tangent of the angle when the washer just begins to slip). Materials include: rubber, glass, wood, and teflon.
  • Use angle ruler (shown in photo) to measure angle.
  • Materials located in L02, section B3. Angle ruler in L45, with rulers.
olive oil fluorescence 2

Olive Oil Fluorescence

olive oil fluorescence 2

olive oil fluorescence

  • Olive oil fluoresces when illuminated by light within a certain frequency range. Violet light causes fluorescence, but attenuates quickly. Green light causes fluorescence but doesn’t attenuate. Red light scatters but does not fluoresce or attenuate.
  • Oil and lasers in L01, section B5 (or B6).

Faster-than-g Falling Chain


  • Hold both ends of the chain- one end in each hand- so that the chain hangs freely and forms a U shape.
  • When one end of the chain is released it accelerates toward the ground faster than g. To prove it, drop an object simultaneously with the chain end, and listen to hear which one strikes the ground first.
  • Requires standing on ladder.
  • Chain located in L02, section B3. Plastic balls in section A2.

Tonic Water Fluorescence



Light, of high enough frequency, will cause quinine (found in tonic water) to fluoresce. The emitted light is a brilliant blue color. Also works with a black light.

Location:  Tonic water and violet laser pointer in L01, section B4. Black light in section A1 (or A2).

laser refraction 2

Refraction with Water

smoke on the water 1

laser refraction 1

laser refraction 2

total internal reflection

  • Refracted beam of light made visible with water, coffee creamer, and smoke.
  • Fill container half way with water. Mix in 1 or 2 pinches of non-dairy coffee creamer.
  • Use smoke maker (blue device in top photo) to fill container with smoke. Place lid on container to contain smoke.
  • Use laser pointer to create beam of light.

impulse block 1

Impulse Block

impulse block 1

  • Two different balls can be rolled down incline to collide with wooden block. When rubber, bouncy ball collides with block, block tips over.
  • However, when non-bouncy ball collides with block (looks identical to bouncy ball) block does not tip over. Balls have same size and weight.


  • Balls and block located in L02, section B5.
  • Track in Lo2, section B2.
  • Jacks in L35, section D1.
hammer balance

Hammer Balance

hammer balance

hanging hammer 1


hanging hammer 2

  • Hammer balances in a manner that appears impossible, but does so because 1) center of mass is not beyond edge of table, and 2) angular displacement of hammer increases potential energy of system, meaning system is stable. Stick end can be pushed very close to table edge, as seen in above photo.
  • Demo located in L02, section B4
air foil 1

Air Foil

air foil 2


air foil 1



  • When air is blown across surface of paper foil, high pressure results on lower side and low pressure on upper side, creating lift.
  • Located in Lo2, section D1 or D2. Air source in L35, B3 corner.



smoke rings 1

Smoke Rings

smoke rings 1


smoke rings 2

  • Fill container with smoke using smoke maker (blue thing on right in above photo).
  • Tap the diaphragm on the bottom of the bucket to produce vortices of smoke. The gentler the tap the slower the ring velocity.
  • Use a black background for best visibility.
  • Located in L02, section D1 or D2
sound of g 2

Sound of g

sound of g 1

sound of g 3

sound of g 2

  • Nuts are tied to two separate ropes. Spacing between nuts on rope 1 is constant; spacing between nuts on rope 2 goes as the square of the distance from the end of the rope.
  • Hang ropes vertically and drop onto wooden platform. When rope 1 falls sound made by nuts (hitting board) increases in frequency, indicating acceleration of rope. When rope 2 falls, the nut-hitting-board sound is periodic, due to r^2 spacing.
  • Note: When hanging string, first nut (on bottom of string) rests upon board. So first nut does not fall- merely used as an a position anchor.
  • Located in L02, section B3.

light bulb energy usage2

Light Bulb Energy Usage



light bulb energy usage

light bulb energy usage2

  • When bulbs consume the same amount of power (same wattage) their brightness differs substantially- the incandescent bulb is much dimmer than both the compact fluorescent and the LED, which are of comparable brightness.
  • Bulb power can be adjusted using sliders. Meter connected to bulb tells both watts and volts.
  • Located in L01, section B5




inertia break

Inertia String Break

inertia break

inertia break2

  • Hang a 1 Kg mass by a piece of masking tape (just wrap the tape around the hook of the weight).  With the weight dangling, yank upwards on the tape. The tape will break if the yank is quick enough.
  • Instead of yanking, hoist weight upwards slowly and tape will not break.
  • Tape breaks much more easily than string, and is easier to hold on to.


  • Masking tape located in L35, above the sink, on a peg.
  • Weight located in L02, section A1.



Speed of Light in H2O

Speed of Light in Water

Speed of Light in H2Ob

Speed of Light in H2O

  • Use speed of light set-up to measure velocity of light (pulsed laser, photo detector, oscilloscope). Two different light paths are required. Place a tank of water in one of the paths and observe the time delay that results. Velocity of light through water can be measured and compared to theory.
  • See lab lecturer for set up details.



  • Use detector to measure radiation at various distances from radioactive source; instead of varying distance use thin sheets of aluminum and vary thickness of barrier.
  • Detector and sources located in radioactive materials storage room. Thin sheets of aluminum in L35.

Poisson Spot





  • Shine coherent light onto a spherical object and a dim spot of light appears in the center of the object’s circular shadow. This spot is called a Poisson spot, or Arago spot, and can be explained using the wave interpretation of light.
  • Green or red lasers, diverting lens, optics track and components located in L35, section A. BB in glass slides located in L01, section B6.
1 over r-squared

1 over r^2 lights

1 over r-squared 2

1 over r-squared

  • Show, qualitatively, that light intensity falls off as 1 over the square of the distance.
  • Bulbs have equal luminosity. When covered with translucent domes smaller dome is noticeably brighter. Amount of light is equal, but larger surface area means lower light density, i.e. lower brightness.
  • Located in Lo1, section B6.
marble drop

Marble Bounce


  • Glass has a very high coefficient of restitution. This makes glass marbles very bouncy, if dropped on very hard surfaces. When a marble is dropped onto the head of a hardened steel hammer (as shown on the left in the above photo) the marble bounces almost back up to the height of release. If dropped onto the surface of non-hardened steel (as shown on the right) the marble only bounces about 2/3 of the way back up.
  • Located in L02, section B4
chain fountain

Chain Fountain

chain fountain

Few demos are as simple and surprising as this one.

  • Chain appears to levitate as it falls out of cup.
  • Elevate cup above floor 5 to 7 feet. Pull end of chain out of cup to begin initial descent. Chain will self-siphon.
  • While the chain falls at an accelerating rate, a standing wave develops above the lip of the cup and levitates.
  • See a brief youtube video here.
  • See a slow-mo video here, with a conceptual explanation.

Located in L02, section B-3.


Induction coils

Induction Solenoids

Induction coils


  • When current through a solenoid changes, a magnetic field is induced within the solenoid. If two solenoids are concentric with each other, the induced field in one solenoid produces a changing current in the other.
  • Connect a power supply to one solenoid and a galvanometer to the other.
  • Unless steel rod is inserted in innermost cylinder (shown above), induced magnetic field is too week to produce a noticeable effect. Steel rod greatly enhances effect.


Solenoids: L01, section

B-2Galvanometer: L35, section F-3

Power supply: L35, section F-1




Wimshurst Generator

Wimshurst Generator Demo Picture
Wimshurst Generator Demo Picture

  • Hand-cranked charge separator. Generate large sparks for
    entertainment or for use in various electrostatic experiments.
  • Use generator to charge capacitor plates or Leyden Jar.
  • Dip conductive pith ball in between parallel plate capacitor
    hooked to W-generator; crank W-generator; pith ball bounces back and forth
    between plates.
  • Located in L01; section A2, covered in plastic bag.

Van de Graaff Generator


Van de Graaff Generator Demo Picture

  • Principle: Static electricity is cool.
  • Located in L01, section A2
  • Van de Graaf accessories are located beneath Van de Graaff
    generator in plastic containers.

Some ideas for experiments beyond the typical shock-myself-and-my-students:

  • Bend a paper clip into an L shape and tape it to the charged sphere to create
    an ion gun; point the paper clip at the palm of your hand to feel the “ion
    wind”. Point the paper clip at your shirt to charge your shirt up- after
    30 seconds shirt should begin sticking to your chest.
  • Place a cup of styrofoam peanuts, or a stack of styro or aluminum plates
    on top of the sphere, turn on generator and watch stuff fly.
  • Dim the room lights, touch one end of a fluorescent bulb to the charged
    sphere and the other end of the bulb to the small discharging sphere. Bulb
    will flicker.
  • Using a squirt gun shoot a stream of water past the charged sphere; water
    should ionize and stream will disperse.

Additional Van de Graaff demo ideas




Hydrogen Fuel Cell 1

Hydrogen Fuel Cell


Hydrogen Fuel Cell Demo Picture
Hydrogen Fuel Cell Demo Picture

Located in L35, section H-3.


Very nice (and expensive) demo. Please handle with care.

For detailed operation instructions see Instructions booklets-
one for fuel cell stack, and one for electrolyzer.

  • Connect fuel cell stack to electrolyzer as shown in above picture.
  • Fill tall cylinder with distilled water up to the 0 cm mark.
  • Fill the water reservoir of the electrolyzer with deionized water up to the -A- mark.
  • Connect the power supply, or solar cell, to the positive and negative terminals of the electrolyzer. Current causes water to split into oxygen and hydrogen. The oxygen escapes into the atmosphere, and the hydrogen accumulates in the gas storage tank (tall cylinder).
  • When hydrogen gas is allowed to flow into the fuel cell stack (see fuel cell operating instructions booklet; pg 9), the voltage difference that develops across the stack can be used to power the fan (see above picture).
  • Also, the voltage difference across each individual cell can be measured with a volt meter.

For Demo and Lab ideas see “Fuel Cell Technology for Classroom
Instruction” booklet.

Astro blaster



Astro-Blaster Demo Picture

  • Purpose: Illustrate principles of conservation of momentum
    and energy, specifically during the creation of a supernova.
  • Hold tip of AstroBlaster as shown; release when hanging straight
    down. Blasted capsule can reach heights of over 5 times the drop height.
  • May consider wearing protective goggles for this one.
  • Location: L02, section B5


high low road

High/Low Road


High/Low Road Demo Picture

  • Purpose: Demonstrate properties of gravitational potential
  • Balls start moving and end with identical velocities, but ball on longer track traverses path more quickly.
  • Prove that balls end with identical velocities by showing they fall the same distance from the end of the track. Use carbon paper to show location of impact. 
  • Located in L02, section B2


Hubble flow2

Hubble Flow


Hubble Flow Demo Picture Hubble Flow Demo Picture 2

  • Flow of medium is indicated by motion of objects within medium,
    analogous to Hubble flow of space.
  • Stir water. Direction of flow isn’t discernable until small,
    plastic pieces are sprinkled in.


  • Tub: L35, section I2
  • plastic pieces: L01, section C2


cloud chbr1

Cloud Chamber

Diffusion Cloud Chamber

cloud chbr1

  • The Pasco Diffusion Cloud Chamber is very easy to set up and operate- does not require use of dry ice or liquid nitrogen.
  • Use pump to circulate ice water through base. Peltier device cools chamber base down to -35 C.
  • Soak paper liner with isopropyl alcohol (93% or higher), and pour alcohol into bottom of chamber 1 mm deep.
  • Cloud sets up in 10-15 minutes. Cosmic ray tracks (mostly thin streaks) should readily appear.
  • Use radiation sources to see alpha tracks (fat streaks).
  • Needle source is lead 210; disk source is americium 241, extracted from a smoke detector.
  • Footage of this cloud chamber in operation: https://youtu.be/1ss5DBGWMo4 (sign in to YouTube to view).
  • Located in L01, section C1.

radioactive sources

cloud chbr2


Petri dish cloud chamber

little cloud chamber



  • Soak black paper with ethanol or highly concentrated isopropyl alcohol (93% or higher).
  • Insert radioactive source (Pb-210) into hole on side of container.
  • Place chamber on slab of dry ice.
  • After 5 or 10 minutes of cooling down, clouds of supersaturated alcohol will form near bottom of container. Alpha particles or cosmic rays that streak through alcohol cloud ionize alcohol, causing it to condense along particle’s path. 
  • To illuminate tracks (to make more visible) shine a flashlight, or cell phone light, into side of container.
  • Getting alcohol cloud to form is a little bit tricky. Before attempting this demo in class, try it out.

Located in L01, section C1.



Neon Wand 4

Neon Wand


Neon Wand Demo Picture

Neon Wand Demo Picture 2

  • Transparent glass tube containing neon gas glows orange when
    shocked by Van de Graaf (Be careful not to shock yourself!- tape the wand
    to an extension rod, like a meter stick, if you’re worried about getting shocked). This can be done with the any of the spectral tubes.
  • Located in L01, section A-2, bottom shelf, in tub with other
    Van de Graaf accessories.
  • Cute video about the atomic physics of neon signs. http://www.youtube.com/watch?v=zPDoBjlpxXY


Mercury _ White Light

White light / Mercury lamp


White/Mercury Lamp Demo Picture

  • Located in L01, section C1.
  • Danger: Even momentary exposure to ultra violet rays
    causes severe eye damage. Always keep the opening of the light box covered
    with one or more glass plates or filters when unit is used as light source. Never look directly at the Mercury Vapour lamp if
    the glass plate is removed.


Optical Rotation 4

Optical Rotation Bowl


Optical Rotation Bowl Demo Picture
Optical Rotation Bowl Demo Picture 2
Optical Rotation Bowl Demo Picture 3

  • Illuminate bowl with polarized light. Bowl, and objects within,
    appear multi-colored when viewed through a polarizer. Rotate polarizer to
    see colors change.
  • Phenomenon is the result of optical rotation. Linearly polarized light gets rotated by molecular composition of bowl; extent of rotation
    depends on wavelength of light, causing angular separation of colors.
  • Located in L01, section B5.



Barber Pole Demo

Barber Pole


Barber Pole Demo Picture

  • Shine polarized light through a bottle of corn syrup. Bottle of syrup appears multi-colored when viewed through a polarizer. Rotate polarizer to see colors change.
  • Phenomenon is the result of optical rotation. Syrup rotates linearly polarized light; extent of rotation depends on wavelength of light, causing angular seperation of colors.
  • Located in L01, section B5.


polarization 3 2010

Birefringence & Optical Activity


Birefringence and Optical Activity Demo Picture

Birefringence and Optical Activity Demo Picture 3
Birefringence and Optical Activity Demo Picture 2

  • Set contains: Polarizers, Mica Wafers, selenite, calcite samples, Benzoic Acid wafers, stressed plastic, cellophane, and corn syrup.
  • View various objects between two polarized lenses; rotate a lens to see change in color patterns.
  • Phenomenon is the result of optical rotation. Linearly polarized light rotates as it passes through these materials. Extent of rotation depends on wavelength of light, causing angular separation of colors.
  • Located in L01, section B4



Scattering Sunset







Demonstrate why the sky is blue and sunsets are red.

Supplies needed

  • tank, water, artificial creamer, flashlight (pretty simple!)
  • Use polarizer to show that scattered beam is polarized.
  • Located in L01, section B6.



Scattering and Absorption


Scattering and Absorption Demo Picture

Scattering and Absorption Demo Picture 2

Scattering and Absorption Demo Picture 3

  • Red laser light penetrates milky solution and is slightly attenuated (top photo).
  • Blue dye absorbs red light but not green light. Red laser attenuation is much greater than green in blue-dye/water solution.


  • Lasers: L35, section A-5.
  • Dye: L35, in cabinet above sink.
  • Beaker: L35, section G-3.



Phantom Crystals 3

Phantom Crystals

Phantom Crystals Demo Picture 2

index matching gel crystals 2

index matching gel crystals 1

  • Phantom Crystals are carbon-based polymers that absorb up to 300 times their weight in water. A fully saturated crystal in a glass of water is almost invisible, as light passes through it without being refracted. But when exposed to air, the water soaked crystals are clearly visible, because air’s index of refraction is very different from that of water.
  • Located in L01, section B-5


Atomic Spectra

Atomic Spectra


Atomic Spectra Demo Picture

  • View Balmer series using hydrogen light source, diffraction
    grating, and optics rail.


  • Optics rail parts: L02, section B6
  • Spectrometer grating (small one, in above photo): L35, section A5
  • Spectrometer grating (large, hand-held, good for demos): L02, section C1
  • Spectral tubes and power supply: L35, section G1


Water optics 3

Water Optics


Water Optics Demo Picture 2

Water Optics Demo Picture

  • Shine laser beam into a falling stream of water; beam follows
    curve of stream due to total internal reflection.
  • Water Optics container located in L01, section B4. Laser
    in L35 section A5.


1 over d^2

1/d^2 Dependence


1/d^2 dependence Demo Picture

  • Purpose:Demonstrate 1/d^2 dependence of brightness.
  • Adjust distance of light detector, current meter indicates
    brightness of light.


  • light detector: L35, section G1
  • light bulb, socket, and clamp: L35, section D2
  • ring stand: L35, section A4
  • 2 meter stick: L35, section A2


Spherical Aberration 1

Spherical Aberration


Spherical Aberration Demo Picture
pherical Aberration Demo Picture 2
pherical Aberration Demo Picture 3

  • A perfect lens focuses all incoming rays to a point on the
    optic axis. A real lens, with a spherical surface, suffers from spherical
    aberration: it focuses rays more tightly if they enter the lens far from the
    optic axis, and less tightly if they enter closer to the axis.
  • Located in Blackboard Optics; L01, section B6



Optical Fiber in Oil


Optical Fiber in Oil Demo Picture
Optical Fiber in Oil Demo Picture 2

Optical Fiber in Oil Demo Picture 3

Optical Fiver in Oil Demo Picture 4

  • Shine laser through bent optical fiber and total internal reflection is observed. Place optical fiber in tub of oil and laser is no longer internally reflected because index of refraction of oil is similar to that of optical fiber.
  • Oil and optical fiber located in L01, section B5. Red pasco
    laser located in L35, section A5. Ring stand in L35. Clamp in L35, section
  • Bring paper towels for clean-up.