The units of magnetic flux are webers (MKS), or maxwells, found by integrating one
gauss over one square centimeter. The vector H is called the magnetic field. It it related
to B by the well-known relation, H ¼ B=m. The MKS units of H are newton/weber
or amperes/meter, and the CGS units of H are oersteds ð1A=m¼4 103 oerstedsÞ.
There are a variety of magnetic sensors which can be used to measure dc and ac B fields
in space. The first and most basic means is the solenoidal search coil. If the B field
is homogeneous over the area of the coil, a time varying B field will induce an open
circuit EMF given by the well-known relation: