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Re: Alternating Current

I suggest using the CBL to analyze the light from a classroom overhead
projector that uses a "low voltage bulb". The ripple frequency is found to
be close to 60 Hz. There must be a diode in series with the bulb so that the
bulb is lite by a half wave rectified power source. Does the smaller ripple
freq make the bulb last longer?? Does the smaller ripple freq provide a more
peaceful setting for a seizure prone child?? Why does the design call for
the "low voltage bulb?
Charlie

-----Original Message-----
From: JACK L. URETSKY (C)1998; HEP DIVISION, ARGONNE NATIONAL LAB ARGONNE,
IL 60439 <JLU@HEP.ANL.GOV>
To: PHYS-L@LISTS.NAU.EDU <PHYS-L@LISTS.NAU.EDU>
Date: Saturday, January 30, 1999 1:23 PM
Subject: Re: Alternating Current


Reply to Mike Monce:
But the uncertainty principl is (delta f)*(delta T)=1, so the
differences
have already been taken. This is, by the way, the Heisenberg uncertainty
principle
in disguise.
There is another limitation having to do with the sampling interval
(the
Nyquist criterion) that can degrade the measurement before one reaches the
fundamental limit that is set by the Heisenberg relation.
*******************************************************
If f = 1/t , then isn't delta f = delta t/ t^2 (ignoring the
minus sign)?? So if the interval is .01 sec and can be controlled, say,
to within a millisecond, then we get delta f = .001/ (.01)^2 = 10 Hz,
which explains the frequency seen; 120 +- 10 Hz.


Mike Monce
Connecticut College
*********************************
Regards, Jack

"I scored the next great triumph for science myself,
to wit, how the milk gets into the cow. Both of us
had marveled over that mystery a long time. We had
followed the cows around for years - that is, in the
daytime - but had never caught them drinking fluid of
that color."
Mark Twain, Extract from Eve's
Autobiography