Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

Re: simplier is mor difficult




LUDWIK KOWALSKI writes:
.. By the way, Herb, when will the correct answer to your bar magnet
problem be posted? Are we allowed to think in terms of the N and S poles?


The original problem that I posted concerned a bar magnet allowed to fall
vertically through a solenoid and continue falling a short distance after
emerging from the bottom. Graph the voltage induced in the coil vs the
time of fall.

Since posting the problem, I have been hunting through my files for the
oscilloscope displays that my students photographed. No luck yet but I'm
still trying to find them.

As I remember it, the graph started from zero, showed a positive
acceleration curve until the falling magnet reached a point near the
center of the of the coil.
Then there was a sudden drop of the graph line to a negative point far
below the x axis. The last portion of the graph was an upward curve
approaching the the x axis, as the induced voltage approached zero.

Herb Gottlieb from New York City
(Where our cluttered files become even more cluttered each year)