# Magnetic flux density and Hall probe

1. Apr 7, 2005

### briton

I'm planning an investigation on how magnetic flux density midway between opposite poles of 2 bar magnets varies with separation of the bar magnets (using a Hall Probe). [simply as shown in attachment]

To do this, I'll need to calibrate a hall probe (which I think is done by working out the p.d. (Hall pd) at a known magnetic field strength).

My initial thoughts were that I could use a long straight wire of known current, and use $$B \ = \ \frac{\mu_0 I }{2 \pi \ r}$$
however, this would not work would it? Due to non-uniform magnetic field.

Is the best approach to use a "Helmholtz coil" to get a uniform field- and use the formula given here: http://en.wikipedia.org/wiki/Helmholtz_coils ?

I've never come across this before, so any help / hints would be appreciated. Thanks.

#### Attached Files:

• ###### magflux.JPG
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Last edited: Apr 7, 2005
2. Apr 12, 2005

### MightyMeanie

gee u got this paper early