Using a Hall Probe (Cambridge (CIE) A Level Physics): Revision Note

Measuring magnetic flux density using a Hall probe

• A Hall probe can be used to measure the magnetic flux density between two magnets based on the Hall effect

• It consists of a cylinder with a flat surface at the end

Hall probe

A Hall probe consists of a flat surface and is held so the magnetic field lines are perpendicular to it

• To measure the magnetic flux density between two magnets, the flat surface of the probe must be directed between the magnets

  • This is to ensure the magnetic field lines pass completely perpendicular to this surface

Hall probe in a magnetic field

The Hall probe creates a Hall voltage when placed in a magnetic field

• The probe is connected to a voltmeter to measure the Hall voltage

• If the probe is not held in the correct orientation (perpendicular to the field lines), the voltmeter reading will be reduced

• Since the Hall voltage is directly proportional to the magnetic flux density, the flux density of the magnets can be obtained

• A Hall probe is sensitive enough to measure even the Earth’s magnetic flux density