Entries by rude man

How to Recognize Split Electric Fields

Introduction In a previous Insight, A New Interpretation of Dr. Walter Lewin’s Paradox, I introduced the fact that there are two kinds of E fields.  One (Em) is generated whenever a source of emf is produced.  The other (Es) is the electrostatic field.  The Es field always terminates on free charges; the Em does not. …

A New Interpretation of Dr. Walter Lewin’s Paradox

Much has lately been said regarding this paradox which first appeared in one of W. Lewin’s MIT lecture series on ##{YouTube}^{(1)}##.  This lecture was recently critiqued by C. Mabilde in a second YouTube video and submitted as a  post in a PF ##{thread}^{(2)}##.  The latter cited a third source, that of K. T. McDonald of…

Modulation vs. Beating Confusion

A long time ago I read a paper in the IEEEProceedings recounting the history of the superheterodyne receiver. Overall it was a very interesting and informative article, with one exception: in it the author remarked that the modulation (or mixing) principle was really nothing new, being already known to piano tuners who traditionally used a…

Misconceiving Mutual Inductance Coefficients

  A commonly used formula for mutual inductance M between two nearby coils L1 and L2 is M = k√(L1*L2). This formula however assumes equal percentage flux linkages between the two coils. This requirement is often omitted in several of the references I have looked at. That this requirement is not necessarily met can be…