Faraday Disc

Faraday DiscIn 1831 Michael Faraday, having discovered the law of electromagnetic induction, apart from other experiments made a demonstrable device of converting mechanical energy into electric energy - the Faraday disc. The device was extremely inefficient, but its value was in moving forward the science. The device actually had a lot in common with the Burlow wheel. The law of electromagnetic induction, formulated by Faraday, contemplated the conducting contour, crossing the magnetic field lines. However, in the Faraday case the magnetic field was directed along the rotation axis and the contour remained immobile regarding the field. It was most surprising that the rotation of the magnet along with the disc caused the EMF to appear within the motionless external circuit. That was the Faraday paradox, which was solved several years after his death upon discovery of the electron, bearing the electric charge, the motion of which produces electric current in metals. The electrons within the disc are affected by the Lawrence force, being the vector product of the magnetic field voltage and the speed of the electron movement along with the conductor as the result of the disc rotation. The force was directed along the disc radius. As the result of the rotation EMF appears between its edge and its center. Unlike other electric machines the generator has a very low EMF ranging from fractions of a volt to several volts by low internal resistance and strong current. The uniformity of the current obtained, the lackof necessity to commute it by means of a rotor collector or rectify the alternate current, obtained by other machines with external commuting and electronic devices, high loss of energy due to reverse currents along the disc, heating it uselessly. The problem may be solved partially by means of motors and generators with liquid conducting plough along the disc perimeter. The combination of these properties makes the generator fir for a very narrow sphere of use. Due to the reversibility principle of the electric machines a unipolar electric motor may be possible. The device is of interest to researchers, as it presents a current generator model near to perfection.
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