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Using a Hall Probe (CIE A Level Physics)

Revision Note

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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

A Hall probe

Hall probe diagram, downloadable AS & A Level Physics revision notes

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 so the magnetic field lines pass completely perpendicular to this surface

Hall probe in a magnetic field

Hall probe between magnets, downloadable AS & A Level Physics revision notes

The hall probe creates a hall voltage when placed between 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

Worked example

A Hall probe is placed near one end of a solenoid, as shown in the diagram.WE Using a Hall Probe question image, downloadable AS & A Level Physics revision notesThe Hall probe is rotated about the axis XY.State and explain why the magnitude of the Hall voltage varies.

Answer:

  • The Hall voltage depends on angle between the magnetic field and the plane of the probe
  • The Hall voltage reaches a maximum when the field is perpendicular to the probe
  • The Hall voltage is zero when the field is parallel to the probe

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Ashika

Author: Ashika

Ashika graduated with a first-class Physics degree from Manchester University and, having worked as a software engineer, focused on Physics education, creating engaging content to help students across all levels. Now an experienced GCSE and A Level Physics and Maths tutor, Ashika helps to grow and improve our Physics resources.