I don't see how that can work,as the magnetic field is uniform throughout the whole disk.
There IS a uniform field there and this is precisely why it DOES work. I gather from your responses that you did not conduct any research like I suggested? This is like saying a voltage and current can be produced by running a magnet along the length of a wire.
Who said that there isn't a voltage produced this way? Obviously it is not produced across the length of the wire, so then where CAN it be measured? And if what you say is correct,then why would the polarity change by spinning the disk in the opposite direction,as the electrons are still moving within the same uniform magnetic field.
Conduct a little research. Basically the force direction experienced by the charges is dependent on the direction the charges move. You can even use the right hand rule to determine the direction of force; point your fingers in the direction the charges travel. Curl your fingers toward the direction of the B field (N-S). Now your thumb points in the direction of the force. Here are a few links to get you started: education portalHyperphysics
uwinnipegright hand rulesst mary'sIf the theory of relative motion between a charged particle and a magnetic field was not predictable and controllable, CRT's for eg. would not have been invented. If you spin an aluminum disk and bring a magnet close to that spinning disk,it will experience the Lorentz force,but if the magnet is attached to the disk(spins with the disk),the disk will not experience the Lorentz force.Also most say there is no CEMF(backEMF) with the HPG,and some say that there is.
I'm almost afraid to open this can of worms, but study eddy current brakes. Lenz's law takes effect when you have a stationary mag field that is not across the whole disc. This creates localized current loops in the disc that generate their own magnetic fields opposing the field of the fixed magnet, and hence the resulting drag. In this case there IS a build up or changing magnetic field experienced by the electrons in the disc, and localized current loops are induced in it as a result. In the case of the Faraday disc, the field is uniform across the entire disc and there is little to no fluctuation in the mag field seen by the electrons. There are two modes of electromagnetic induction: 1) Motional. This pertains to the magnetic force on the charges in a moving wire (such as Faraday disc). Note that the magnetic field in this case does NOT have to be changing in strength for there to be an induced emf. There is relative movement, and that is all that is required. 2) Varying field. This pertains to cases where the magnetic field is changing in intensity which creates a changing electric field. This changing electric field induces an emf in a conductor that is coupled to it. Transformers are a good example. Quiz: When you swipe a magnet across a wire, what mode of induction are you creating, 1) or 2)?
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Topic: HPG and the magnet. (Read 8017 times)
