b-field

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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

 

 

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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.

 

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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

 

 

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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)

 

 

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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.

 

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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.

 

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B-field of Current

 

B-Field of Current demo picture

  • Purpose: Illustrate shape of B-field around current carrying
    wires and show similarities to B-field produced by permanent magnets.

Location

  • Field demonstrators, iron filings, solenoid, perm. magnets,
    mini-compass: L01-section B2
  • Power supply: L35-section F1