is at the centre of the system. The magnetic flux density does
not depend on the angle f, so only the components Bz (z, r)
and Br (z, r) are measured.
Clamp the Hall probe on to a support rod with barrel base,
level with the axis of the coils.
Secure two rules to the bench (parallel or perpendicular to one
another, see Figs. 3–5). The spatial distribution of the magnetic
field can be measured by pushing the barrel base along
one of the rules or the coils along the other one.