Tinman asks: How ever,there seems to be a bit of a mystery here,as the current in the secondary is leading in phase when the load is reduced. This brings the question-->how can it be recieving the magnetic field from the primary before the primary starts to produce current?. I'm not sure; but here is a possible answer. We sometimes think that electromagnetic induction requires a significant but changing Magnetic field B to be present, as when moving a permanent magnet through a coil of wire. But Faraday's law of induction does not require a significant (non-zero) B, it just requires that the magnetic field (or better, flux) be CHANGING. The more rapid the change, the larger the Electromotive force E* E* = - N d(phi)/dt Note that B does not appear; so the magnetic field passing through the coil may be ZERO, as long as it is CHANGING. So perhaps, tinman, you have a large change in B coinciding with ~zero B field, in which case the induced current in the secondary can be large (even though B is approximately zero). This is actually a very interesting case, more generally, rather than having a growing magnetic field to cause an induced current, simply have a rapidly varying B that stays at approx zero - oscillating around zero -- and look at the induced current. Pressing further, a very small but rapidly oscillating current in a one-or-few loop primary at high-frequency may induce a large oscillating current in a secondary (approx. the same number of loops as the primary, say). IDk, something I haven't really thought much about/along this line before...
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Topic: Advanced and Delayed magnetic fields (Read 13438 times)
