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Charged Sheet

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

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Mylar strands align with electric field.

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

  • Located in L01, section A-2
Jumping ring

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.

 

Parallel Currents

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.

 

teachspin

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.

 

current balance

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.

 

Faraday Cage

Faraday Cage

 

Faraday Cage demo picture

  • Use the cage in conjunction with Van de Graaff to demonstrate
    electrostatic shielding.
  • Place a hand-held radio inside the cage to demonstrate electromagnetic
    shielding (radio in cage should pick-up no signal).
  • Located in L01, section A2.

 

Vandegraaff

Van de Graaff Gen.

 

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.