I am continuing this thread as the origin of my homopolar generator is not clear. What is the principle of a homopolar generator like the Faraday disc? The traditional explanation is that the electrons in the disc moving in the field of the magnet, are subject to the Lorentz force, perpendicular, and therefore move between the centre of the axis and the periphery of the disc, where the sliding contacts are. Now if we place ourselves in the reference frame of the disc, we see the external circuit connected to the sliding contacts rotating, and the Lorentz force is seen exerting itself on the electrons of the circuit external to the disc. The effect would thus be reciprocal. But beware, when we take a small circular magnet and a large disc, the sliding contacts are outside the magnetic field and yet we still have the effect without being able to adopt the explanation of the Lorentz force seen from the reference frame of the disc, so the explanation would not be reciprocal. A less traditional but nevertheless academic explanation is that the electric circuit cuts the magnetic flux, see diagram. On the loop ABCDO, we look at the cut flux at time t and t+dt. The segment DO has rotated by an angle dθ = ω.dt, which adds a new segment DD' to the loop. The magnetic flux through the loop ABCDD'O is Φ.B(t+dt) = B.r².dθ/2 = r².B.ω.dt/2 and integrating, EMF = -dΦ/dt = -r².B.ω/2, where r is the radius of the disc. From this we can formulate very simply the general principle of operation of a homopolar generator: we need a magnetic flux through an electric circuit in two parts, one of which is movable relative to the other.The flux being conservative, whether it is one or the other part that we take as reference, each one sees the other one cutting the same flux, which generates the electromotive force. The next step : to re-analyse my generator using this principle. 
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Topic: Homopolar Generator, a new one? (Read 4233 times)
