What is The Hall Effect?

The Hall Effect was discovered in 1879 by American physicistEdwin Hall, who was working on his doctorate at the time of the discovery. In the late 1800s, his findings were ground-breaking,but there were no real life applications of what he had found, as electricitywas not widely used, and the electron had not been officially discoveredeither. It would not be until severaldecades later that his work would be fully understood and appreciated.

To discover this without knowing that electrons existed isamazing, as it is the electrons reacting to the magnetic field that causes theHall Effect. His research would not bewidely understood or used for nearly two decades until the existence ofelectrons was confirmed. Armed with thisnew knowledge and Hall's research, physicists could now start to understandthis effect and what was causing it, as well as how this discovery could beused. Further research intosemiconducting materials enabled scientists to progress with the development ofHall Effect sensors, named in recognition of Hall's pioneering work.

Hall Effect sensors use the difference in voltages on eitherside of the semiconductor to determine the location of a magnet (which is usedas the other part of the sensor system and the component that needs locating ormeasuring). A constant charge is fedthrough the semiconducting component of the sensor, and then introduced to amagnetic field. The magnetic fieldforces the charged particles to either side of the material, creating adifference in voltage across the semiconductor.The size of the voltage is proportional to the size of the magneticfield as well as the size of the current.Knowing the voltage sizes that are present at different points of thejourney of the semiconductor as it nears and moves away from the magnetic fieldmeans the sensor can be set to detect a specific location of the magnet andsemiconductor.

The Hall Effect can be used in both rotary and linearposition sensors; in the rotary application the semiconducting material isplaced in an X shape, and the magnet rotates above this shape. As it moves, the polarity of the magnet willmove with it, creating different voltages at different stages of the rotationacross the semiconductor. Measuring thisvoltage and specifying the location at which the voltage measured should be acertain size means the rotary sensor knows exactly where it is in relation tothe magnet through a rotation of 360°.Linear applications are simpler,nbsp;using the difference in voltage to detect the position of the magnetalong a single plane.

Even though the basic knowledge of the Hall Effect wasdiscovered over 130 years ago and not widely used until the early 20^thcentury, it is still applied today in sensors found everywhere, from hospitalsto factories, cars to smartphones and even in space shuttles.