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1. Introduction
   
   There are many different types of sensing elements used in accelerometers. Hall effect one of the the sensing elements that is used in the design of accelerometers. I find this type of sensing interesting, and therefore, in this wiki page I will discuss briefly the physical principle of sensing based on Hall effect.

   The Hall effect was discovered in 1879 by Dr. Edwin Herbert Hall while he was at Johns Hopkins University in Baltimore. While trying to verify electron flow theory proposed by Kelvin, he found that when a magnet was placed with its fields being perpendicular to one face of a thin rectangle of gold which current was flowing through, a potential difference appeared at the opposite edges. What he found is that this voltage is proportional to the current flowing through the conductor, and the flux density or magnetic induction perpendicular to the conductor. He experiments were successful and well received at the time. [1]

2. Theory of the Hall effect
   
   The Hall effect is based on the interaction between moving electric carriers and an external magnetic field. If an electric current flows through a conductor in an external magnetic field, then a transverse force call Lorentz force caused by the magnetic field will exert on the moving charge carriers, which pushes these carriers to one side of the conductor. A buildup of charges at the sides of the conductors will balance this magnetic influence, producing a measure voltage between the two sides of the conductor. The presence of this voltage is called the Hall effect, and this voltage is the Hall voltage (Vh).
   
   Image Added
                                                                                Figure 1. Hall effect principle with magnetic field present [2]
   
   Figure 1 shows the principle of Hall effect with the direction of current being the conventional current. The magnetic field is perpendicular to both the direction of the current and the Lorentz force.
   
   
3. Hall effect accelerometers

References

1. Bridgemen, P. W. (1939). Biographical Memoir of Edwin Herbert Hall. National Academy of Sciences.
2. http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/hall.html
3. Jacob Fraden. Handbook of Modern Sensors: Physics, Designs, and Applications (4th edition). Springer Publishing
4. http://farside.ph.utexas.edu/teaching/302l/lectures/node74.html
5. http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/hall.html
6. http://sensing.honeywell.com/honeywell-sensing-sensors-magnetoresistive-hall-effect-applications-005715-2-en.pdf

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