Hall-effect devices: A survey

If a magnetic field is applied perpendicular to a current flow in any conductor the moving charges (which constitute the current) are releflected sidewise and build up a potential difference between the two sides of the conductor. The creation of this transverse electric field (perpendicular both to the magnetic field and to the original current flow) is called the Hall effect. This effect has been the mode of operation of many proposed devices. These devices, which will be discussed, have been arbitrarily divided into two groups: Devices which use a constant magnetic field, and devices in which a signal or an oscillator produces the magnetic field. Such a division is not entirely arbitrary, because the first groujrhas inherently a very high limit on the operating frequency; whereas the second group has a considerably lower limit.