A Simple Oersted Apparatus

1
A Simple Oersted Apparatus
2
Experiment Goals

• To demonstrate the circular geometry of the
  magnetic field lines surrounding a
  current-carrying wire
• To provide quantitative data on the radial
  dependence of the magnetic field strength as a
  function of the radial distance from the wire

3
Overview
Push Button
Lucite Supports
Banana Connections
Current-Carrying Wire
Compasses to Sense Field Direction
Support Table
6 V Lantern Battery Current Supply
4
Construction

• Support table constructed from inexpensive
  commercial cutting board and Lucite rod legs
• Very simple to construct, requires a minimum of
  skilled fabrication
• Suitable for student fabrication
• Total cost 25

5
Data

• Ratio of finite wire field to infinite wire
  field 0.9 at
• r 5 cm (calculated)
• Deviation from r -1 attributed to poor Hall probe
  performance
• near the limits of sensitivity (large zero offset
  drift present)
• At 5 cm wire field is comparable to Earths
  field requires
• apparatus to be aligned so Earths field is
  radial to wire

6
Summary and Conclusions

• Apparatus is exceptionally inexpensive and easy
  to construct
• Lantern battery can supply 10 amp for brief
  periods, eliminating the need for an expensive
  high-current supply
• Excellent qualitative demonstration of the
  circular magnetic field line geometry surrounding
  the wire
• Good quantitative data for the radial dependence
  of the magnetic field with distance is possible,
  but requires a high quality Hall probe which can
  measure 0.01 mTesla with good accuracy.
• Actual field is 0.9 of infinite wire field
  calculated from Amperes law at 5 cm