The Hall effect is the production of a voltage difference across an electrical conductor, transverse to an electric current in the conductor and to an applied magnetic field perpendicular to the current. It was discovered by Edwin Hall in 1879

A test during which the output readings are compared with the corresponding standard values of measurand measured by a device is called as Calibration.

Calibration involves comparison of a particular instrument with either (i) a primary standard (ii) a secondary standard with a higher accuracy than the instrument to be calibrated or (iii) a known input source.