The electric conductivity can be then expressed thanks to a matrix. It can also be said that there are in fact two conductivities: one parallel, the other one transversal. For a given pressure, according to the magnetic field value which determines the Hall parameter one, we have two opposite situations :
First configuration: the Hall parameter value is negligible compared to unity. The electric conductivity is reduced to the scalar electric conductivity.
Second configuration : the Hall parameter is high compared to unity
We get the following :
If we want to get high Hall parameter values with modest means (permanent magnets), we have a solution : Work under low pressure. Here under our test bench.