A Hall Probe

[piraterach]

Can you please tell me

1.how to calibrate an uncalibrated hall probe

2. how to use it to investigate the magnetic flux density between 2 permanent bar magnets and how this varies with their seperation

Thanks

Rachel x

[Clanad]

There are simple and complex methods of calibrating the Hall Probe... This one (thanks to Rutgers University Physics Department) doens't require some of the more exotic testing equipment and may work for you, depending on your level of expertise and patience:

Calibration Procedure:
First, you will calibrate the Hall probe by using the Earth�s magnetic field. The probeamplifier will give an output voltage (offset voltage) somewhere between 1 and 5 voltseven when there is no applied magnetic field. To determine the zero magnetic fieldreading for the probe you will rotate the probe horizontally through 360o(degrees). (Use the inscribed line on the bottom of the clear plastic holder in order to align the probe.) Asyou rotate the probe horizontally through the Earth�s magnetic field, you will see a rangeof Hall voltages, say, 2.409V to 2.391V, which averages to 2.400V. Thus the probe has a zero offset, Voof 2.400V. Readings greater than 2.400V indicate a positive field, while those less are negative fields.

Contd.

[Clanad]

Contd.
You will then use the amplitude of the variation to convert the probe voltage reading to the magnetic field in gauss. The full peak-to-peak amplitude variation in the probe voltage corresponds to a change in magnetic field 0.40 G [i.e. the horizontal component of the Earth�s field changes from +0.20 G to -0.20 G as the probe is 1/00 Ampere 5/9 rotated through 360 (degrees). The conversion factor b from probe voltage reading to magneticfield can then be calculated from B = b(V- Vo). In this example b=0.40 /(2.409-2.391) =22.2 G/V. Do the calibration on the �compass� diagram that positions the probe for 12 directions.Before turning on the 5V supply for the Hall probe, disconnect the +12 V lead going to the solenoid. Turn on the supply and set the Fluke multimeter toV(volts DC). Take twelve compass readings and determine Voand b from the voltage range.



The answers to the balance of your query may be found here:

http://72.14.203.104/search?q=cache:DdWL7KFXYuYJ:www.physics.rutgers.edu/ugrad/276/ampere.PDF+How+to+calibrate+a+Hall+probe&hl=en&gl=us&ct=clnk&cd=8