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.

Location

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

 

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

 

Instructions

  • 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

 

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

 

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.

 

Plasma Lamp

plasma ball 7

Plasma Lamp Demo Picture

  • Located in L01, section C2.
  • Lots of information online about these- how they work and what to do with them.
  • Florescent bulbs glow when brought in close proximity to globe.

 

Crossed Polarizers

 

Crossed Polarizers Demo Picture

Crossed Polarizers Demo Picture 2

Crossed Polarizers Demo Picture 3

  • Light is totally blocked when two polarizers are oriented 90 degrees apart. When third polarizer is inserted between the first two at an intermediate angle, light is transmitted.
  • Located in L01, section B-5.

 

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

 

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.

 

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

 

sunset2

 

sunset4

 

sunset3

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.

Location

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

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

Location

  • 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

 

Diffraction of light

 

Diffraction of light Demo Picture

  • Shine laser beam through a variety of diffraction patterns
    to demonstrate properties of single and multiple-slit diffraction.
  • Diffraction Accessories located in
    L01, section B5.
  • Calipers located in L35, section D2.

 

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.

 

DVD Diffraction

 

DVD Diffraction Demo Picture

  • Reflect a laser beam off the surface of a DVD or CD onto a flat, white surface. Space between fringes can be measured to determine spacing of pits in disk.
  • Located in L35, section A5.

 

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.

Location

  • 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

 

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
    D1.
  • Bring paper towels for clean-up.

 

 

Blackboard Optics

 

Blackboard Optics Demo Picture

Experiments Include

  • The laws of reflection
  • virtual image with a plane mirror, convex mirror, and a concave lens
  • focal length of concave and convex mirrors
  • focal length of planoconvex and planoconcave lenses
  • real image formed by a concave mirror
  • simple refraction
  • less dense to more dense medium
  • parallel displacement by a rectangular block
  • semicircular body
  • light incident at center if disc and at right angles to tangent
  • critical angle
  • total internal reflection
  • reversing prism.

Have 2 sets. New set uses magnetic attachments, old set uses suction.

  • Located in L01; section B6

 

Radiation Cans

 

Radiation Cans Demo Picture

  • Cans radiate and absorb heat at different rates.
  • Fill cans with warm, or cool water of identical temperature. Monitor the temperature change with a thermometer, or with a Logger Pro temperature probe.
  • Located in L02, section C-3.

 

Peltier Effect

Peltier Effect Demo Picture

Peltier Effect Demo Picture 2

  • Connect Peltier device to Genecon hand-cranked generator. Voltage polarity is controlled by direction of crank. Temperature of Peltier chip (white square) depends on voltage polarity. Chip can be heated above room temp or cooled below. Chip responds very quickly to voltage increase.
  • Located in L02, section C-3.

 

Absolute Zero

 

Absolute Zero Demo Picture

Theory:

In a gas thermometer, pressure varies linearly with tempurature
(at fixed volume), and is given by P=aT+b, in degrees celsius. One can determine
the value of absolute zero by calibrating the gas thermometer at non-extreme
temperatures and extrapolating the calibration curve to the point of zero pressure
(and hence zero temperature).

 

Procedure:

Fill gas thermometer with air by opening the valve all the way,
then close the valve tightly to seal the bulb. Place the bulb of the gas thermometer
into a water bath of known temperature and record pressure and temperature.
Repeat procedure with at least one more bath of a different temperature. Plot
data, and extrapolate to zero pressure to determine abs zero. To test accuracy
of calibration curve, use gas thermometer to determine temperature of LN2. Should
get something close to -196 degrees Celsius. (However, oxygen will liquify,
causing P vs T curve to become non-linear. So, may not get exactly -196.)

 

Location:

All thermo lab supplies are located in L35, sections G and H.
Saftey glasses are in section C1.

 

 

 

 

Fire Syringe

 

Fire Syringe Demo Picture

  • Demonstrate how rapid adiabatic compression can cause a dramatic
    temperature increase.
  • Ignite a piece of tinder by forcefully ramming a piston
    into an airtight cylinder. Instructions included.
  • Located in L02, section C3.

 

Random Walk

 

Random Walk Demo Picture

  • Located in L01, section C2.

From Wikipedia:

  • The “Bumble Ball” is powered by a motor box with batteries mounted eccentrically. Its power switch consists of a knob that starts the motor when pushed in and stops the motor when pulled out. This causes it to vibrate and bounce about.

 

Thermoelectric Motor

 

Thermoelectric Motor Demo Picture

  • Immerse aluminum legs in baths of different temperatures to produce electrical energy. (May take a few minutes before motor engages. The larger the temperature difference, the better.) Process can be reversed by connecting a low voltage source to the two banana jacks- temperature difference arises between the two legs.
  • Located in L02, section C3.

 

Radiometer

 

Radiometer Demo Picture

  • Temperature difference at edge of metal vanes causes rotor
    to spin.
  • Located in L02, section C3
  • Below explanation taken from Wikipedia (so it must be true).

 

–Explanations for the force on the vanes–

 

Over the years, there have been many attempts
to explain how a Crookes radiometer works:

 

1. Crookes incorrectly suggested that the force was due to the pressure of light.
This theory was originally supported by James Clerk Maxwell who had predicted
this force. This explanation is still often seen in leaflets packaged with the
device. The first experiment to disprove this theory was done by Arthur Schuster
in 1876, who observed that there was a force on the glass bulb of the Crookes
radiometer that was in the opposite direction to the rotation of the vanes.
This showed that the force turning the vanes was generated inside the radiometer.
If light pressure was the cause of the rotation, then the better the vacuum
in the bulb, the less air resistance to movement, and the faster the vanes should
spin. In 1901, with a better vacuum pump, Pyotr Lebedev showed that in fact,
the radiometer only works when there is low pressure gas in the bulb, and the
vanes stay motionless in a hard vacuum. Finally, if light pressure were the
motive force, the radiometer would spin in the opposite direction as the photons
on the shiny side being reflected would deposit more momentum than on the black
side where the photons are absorbed. The actual pressure exerted by light is
far too small to move these vanes but can be measured with devices such as the
Nichols radiometer.

 

2. Another incorrect theory was that the heat on the dark side was causing the
material to outgas, which pushed the radiometer around. This was effectively
disproved by both Schuster’s and Lebedev’s experiments.

 

3. A partial explanation is that gas molecules hitting the warmer side of the
vane will pick up some of the heat, bouncing off the vane with increased speed.
Giving the molecule this extra boost effectively means that a minute pressure
is exerted on the vane. The imbalance of this effect between the warmer black
side and the cooler silver side means the net pressure on the vane is equivalent
to a push on the black side, and as a result the vanes spin round with the black
side trailing. The problem with this idea is that while the faster moving molecules
produce more force, they also do a better job of stopping other molecules from
reaching the vane, so the net force on the vane should be exactly the same —
the greater temperature causes a decrease in local density which results in
the same force on both sides. Years after this explanation was dismissed, Albert
Einstein showed that the two pressures do not cancel out exactly at the edges
of the vanes because of the temperature difference there. The force predicted
by Einstein would be enough to move the vanes, but not fast enough.

 

4. The final piece of the puzzle, thermal transpiration, was theorized by Osborne
Reynolds, but first published by James Clerk Maxwell in the last paper before
his death in 1879. Reynolds found that if a porous plate is kept hotter on one
side than the other, the interactions between gas molecules and the plates are
such that gas will flow through from the cooler to the hotter side. The vanes
of a typical Crookes radiometer are not porous, but the space past their edges
behave like the pores in Reynolds’s plate. On average, the gas molecules move
from the cold side toward the hot side whenever the pressure ratio is less than
the square root of the (absolute) temperature ratio. The pressure difference
causes the vane to move cold (white) side forward.

Both Einstein’s and Reynolds’s forces appear to cause a Crookes radiometer to
rotate, although it still isn’t clear which one is stronger.

 

 

 

 

Sterling Engine

 

Sterling Engine Demo Picture
Sterling Engine Demo Picture 2

 

  • Upper Sterling Engine powered by heat from cup of hot water.
  • Lower Sterling Engine powered by flame.

Location

  • Sterling Engines in L02, section C3
  • Ethanol for flame located in L35, in blue “corrosive
    materials” cabinet.

 

Glowing Pickle

 

Glowing Pickle Demo Picture

6-outlet-perpendicular-power-strip

dill-pickle

  • Skewer pickle across two nails.
  • Send current through pickle using power strip. Use switch on power strip to turn current on and off. Takes about 3o seconds before pickle begins to sizzle and glow.
  •  Sodium D line (yellow light) can be seen using a handheld spectroscope.
  • Warning: Electric shock hazard! Don’t touch pickle while
    it’s being electrocuted. Also, aroma of sizzling pickle not too pleasant.

Location

  • Pickle apparatus (shown above) in L01, section B1.
  • Power strip: L35 section, section D2
  • Pickle: Department fridge.
  • Hand-held spectroscopes: L01, section C1.

 

Transmission Speed

 

Transmission Speed Demo Picture

  • Send a pulsed signal through 400 ft of coaxial line and measure
    the transmission time using an oscilloscope. Part of the signal is sent directly
    into the scope, the other part takes a 400 ft detour through the coax line.
    The travel time is displayed as the time difference between the two peeks.
  • See Jim for coax line; oscilloscope and pulse generator in
    L35, section F.

 

Lenz’s Law Pipe

 

Induction Pipe

  • Use Lenz’s law to explain extremely slow descent of neodymium
    magnet through copper pipe.
  • Hold pipe in a vertical orientation; drop magnet through
    top opening of pipe; watch descent through holes in pipe.
  • Try pipe with continuous slit to see difference in effect.
  • Use copper slug to show speed of descent of non magnetic object.

Location

  • Pipes located in L01, right-hand side between A2 and B1.
  • Magnet in L01, section B2.

 

Lenz’s Law Pendulum

 

Lenz's Law Pendulum demo picture

  • Purpose: Demonstrate the effect of eddy currents on motion of metal pendulum in strong B-field.
  • Pendulum accessories include two interchangeable copper plates, one of which is serrated. Serrated copper plate experiences little resistance to motion through magnetic field.
  • Located in L03

 

 

Jumping Ring

 

Jumping Ring demo picture

  • Fluctuating B field causes ring to either 1) jump off of apparatus, or 2) levitate. 
  • Plug Apparatus into variac; turn variac knob to set current amount; flip variac switch to “on” position to produce instantaneous B field.
  • For added excitement, cool rings with LN2 to increase conductivity.

Notes about use

  • Apparatus is pretty old. Iron rods not securely connected to wooden base. Hold onto base and rods, when lifting or transporting.
  • Do not touch apparatus when variac is on.
  • Jumping ring apparatus located in L01, section B2. Variac
    located in L01, section A1.

 

Induction Firefly

 

Induction Firefly demo picture

  • Light LEDs by moving magnet through coil.
  • LEDs also light when held next to Jumping Ring demo (any fluctuating B field will do).
  • Fireflies located in L01, section B4. Magnet in section B2.

 

Crude Generator and Motor

 

Crude Generator and Motor demo picture
Crude Generator and Motor demo picture

  • Purpose: Demonstrate the importance of electromagnetic induction
    in the operation of generators and motors.
  • Motors (right photo) consist of small coils of wire suspended
    above niodym-magnets; coils rest upon bent wires, and bent wires are connected,
    via clip leads, to a battery pack.
  • Generator (left photo) consists of a small coil of wire suspended
    above a niodymium magnet; coil rests upon leads which are connected to a multimeter.

Location

  • Generators and Motors located in L01, section B4
  • Multi-meter in L35, section F3
  • Battery packs in L35, section E1.
  • Clip-clip cables in L35, section E3

 

Magnet and Solenoid

 

Magnet and Solenoid demo picture

  • Purpose: Demonstrate that changing magnetic flux induces emf.
  • Push magnet into solenoid and galvanometer needle deflects, indicating induced emf; pull magnet out of solenoid and galvanometer needle deflects the opposite way.

Location

  • Solenoid and magnet:L01, section B2
  • Galvanometer: L35, section F3

 

 

Current in Solenoid

 

Current in Solenoid demo picture

  • Purpose: Illustrate principles of electro-magnetic induction.
  • Send current through solenoid and measure direction of B-field
    using B-field indicator (magnaprobe). Place coil of wire in front of solenoid
    and quickly adjust current; galvanometer will indicate induced emf consistent
    with Lenz’s law.

Location

  • Solenoid and wire coil located in L01, section B2.
  • Power supply- L35, section F1;
  • magnaprobe- L35, section E4, top shelf
  • galvanometers- L35, section F3

 

 

Wire loop in B-field

Wire loop in B-field demo picture

  • Purpose: Illustrate that a changing magnetic flux induces an emf.
  • Use a B-field indicator, or compass, to show direction of B-field around magnet; connect coil of wire to galvanometer and move coil in and out of B-field to deflect galvanometer needle.
  • Location: magnet and coil located in L01; galvanometers are in L35, shelf F3, in plastic bin.

 

Electromagnet

 

Electromagnet demo picture

  • Connect a 9V battery ( or power supply) to copper wire coils to create a horseshoe magnet. Vary current to vary strength of magnetic force.
  • Strength of force can be measured using plate with hook (shown above), and spring force scale (L02, section A-1).
  • Located in L01, section

 

Lorentz Force

 

Lorentz Force demo picture

Lorentz Force demo picture 2

Demonstrate Magnetic force on current carrying wire.

 

Location:

  • Neodymium magnet- L35, section E2.
  • Wire: Section E3
  • Ring Stand: Section A4
  • Battery: Electronics Shop.

Note: Blue wire is taped to pencil (with masking tape) for stability.
Clip-clip leads connect battery to wire.

 

 

 

 

 

Force on Wire

 

Force on Wire demo picture
Force on Wire demo picture 2

  • Straight, rigid wire hangs between poles of strong magnet.
    When current is sent through wire, wire is deflected. Direction of deflection
    depends on direction of current.
  • For setup assistance, ask Lab Lecturer.

 

Magnetic Torque

 

Magnetic Torque demo picture

  • Demonstrate torque experienced by magnetic dipole in B-field.
  • Measure magnetic moment of dipole.
  • Show that net force experienced by magnetic dipole
    is zero in uniform B-field, and non-zero in B-field with gradient.
  • See instructors manual for experimental details.
  • Located in L01, section B2.

 

Parallel Currents

Parallel Currents demo picture

force on parallel wires

  • Demonstrate force between parallel currents.
  • Using two power supplies, send current through both stationary and balancing wires.
  • Angle of mirror connected to pivot will change as wires are pulled together or pushed apart due to Lorentz force. A laser beam, deflected by mirror, can be used to show the otherwise imperceptible change of mirror angle.
  • To determine the strength of the Lorentz force: mark the laser position on a distant wall both with and without current- using current that produces attraction, not repulsion. Then, with current off, place small pieces of folded up tin foil on top of movable wire (using platform on wire) until deflection of laser matches that produced by Lorentz force. Weigh tin foil pieces with sensitive digital scale to determine gravitational force.
  • Compare gravitational force to Lorentz force.
  • Distance between wires, and wire length, can be measured using ruler. Current can be measured using Ammeter.
  • Current balance located in L01, section B3.
  • Power supply, laser, digital scale, ammeter, and tin foil in L35.

 

Dip Needle

 

Dip Needle demo picture

  • A magnetic compass mounted in a vertical plane. Displays
    the angle of inclination of the earth’s magnetic field.
  • Located in L01, section A2; in plastic tub.

 

e-beam in B-field

 

e-beam in Bfield demo picture

Purpose: Demonstrate the magnetic deflection of an electron
beam.

  • Crookes tube contains a white screen that fluoresces green when electrons collides with it. High voltage applied across the anode and cathode accelerate electrons through tube. Electron beam can be deflected using magnetic field of bar magnet.

ALWAYS USE THE MINIMUM VOLTAGE AND CURRENT NECESSARY TO OPERATE CROOKES TUBE.

Location

  • Crookes Tube: L01, section B3
  • Kilovolt Power Supply: L01, section A1
  • Magnet: L01, section B2
  • Cables: L01, or L35 (hanging on wall)

 

 

Current Balance

 

Current Balance demo picture

  • Purpose: Demonstrate how the magnetic force on a current
    carrying wire depends on the angle between the current and the external
    B-field.

Location

  • Current Balance in L01, sectionB3
  • Power supply in L35, section F1
  • Multimeter in L35, section F3.