n an ideal world, a Hall element consists of a small slab of semi-conductor material. Current passes from one end of the slab to the other and the voltage on each edge of the slab is the same when no magnetic field is present. If a magnetic field is now applied through the top to bottom surfaces of the slab, a voltage appears across the sides of the slab which is directly proportional to the magnetic flux density or magnetic field strength. In reality, all practical Hall probe elements are only linear within certain limits, normally 1%-2%. The more accurate and thinner the probes, the greater the expense. Most Gauss Meter manufacturers approach this problem by selecting current and Hall probe load resistance to minimise these non-linearity errors.
The Hall probes are connected to Gauss Meters. The Gauss Meters are designed to be linear to make the best use of the non-linear Hall probes.