Physics
Like all dynamos, the Faraday disc converts kinetic energy to electrical energy. This machine can be analysed using Faraday's own law of electromagnetic induction. This law (in its modern form) states that an electric current is induced in a closed electrical circuit when the magnetic flux enclosed by the circuit changes (in either magnitude or direction). For the Faraday disk it is necessary, however, to consider that the circuit(s) consist of each radial "spoke" of the disk connected to the rim and center and then through the external circuit.
The Lorentz force law is more easily used to explain the machine's behaviour. This law, formulated thirty years after Faraday's death, states that the force on an electron is proportional to the cross product of its velocity and the magnetic flux vector. In geometrical terms, this means that the force is at right-angles to both the velocity (azimuthal) and the magnetic flux (axial), which is therefore in a radial direction. The radial movement of the electrons in the disc produces a charge separation between the center of the disc and its rim, and if the circuit is completed an electric current will be produced.
Read more about this topic: Homopolar Generator
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