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Re: Lenz's Law?




Tom McCarthy
Saint Edward's School
1895 St. Edward's Drive
Vero Beach, FL 32963
561-231-4136
Physics and Astronomy

Also, he said the demonstration where an aluminum ring is placed on an iron
core stand that is surrounded by a transformer coil does not truly
demonstrate Lenz's Law. What is your sense on this one, too. What is
demonstrated with the aluminum ring? I know of a couple of things:
One is joule heating from the induced current.

Yes, this is a cool result of this demo. It is astonishing how hot and
quick the ring gets when it is the only turn!

And cooling the ring in LN2 is an exciting way to show the
decreased resistance at lower T for most metals, as well as >illustrating
Ohm's Rule of Thumb that the lowered resistance results >in a greater
current being created by the changing magnetic flux. >(Faraday's Law
of Induction).

How do you monitor the difference between room temperature and LN
temperature currents?


The demos of this that I have seen only send a single pulse of >current
thru the coil, making the Lenz's Law explanation more >beleivable.

Since the ring goes flying high at the onset of the switch, wouldn't this
qualify as the effects of a single pulse?

(But then, I had been laboring under the misunderstanding that the >inertia
of objects, as measured by their mass, was responsible for >their Newton's
First Law behavior.)

I don't understand what you mean here.

Thanks.