The Hall effect can be measured in a ring‐shaped sample placed in an alternating magnetic field normal to the plane of the ring. The resultant circular electric field produces a current around the ring proportional to the time derivative of the magnetic field. This current interacts with the magnetic field, establishing a Hall voltage between the inner and outer radii of the annulus. For extrinsic semiconductors with single effective mass charge carriers, this Hall voltage is, in mks units,
,where μ is the mobility, ω the field angular frequency, Bo
the peak value of the magnetic field, a
the inner radius, and b
the outer radius. This technique eliminates voltages arising due to misaligned probes and end‐effects in the conventional method. In addition, the measurement is independent of the conductivity for the case above. Experimental measurements on germanium, silicon, and indium antimonide rings yield mobility values in agreement with customary results.