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Re: CBL's and photogates



Hi Beth;

I've had success with the photo-gate design and program found in
Brueningsen and Krawiec's book "Exploring Physics and Math with the CBL
system" put out by TI (they have a lot of good ideas- it is worth buying).
They use the light probe that comes with the CBL and a IR LED (Radio Shack
#276-143) in series with a 9V battery and (about) a 390 ohm resistor. Two
caveats: 1) a low battery gives erratic results which students don't
initially recognize as erratic and 2) the CBL takes only 99 data points of
data at a time so there is a trade off between accuracy (for timming fast
things) and how long you can take data which may not be obvious when you
set up an experiment. (So for example you can't expect to get 0.05s
accuracy in a series of measurements over a 10s interval.)

I can give you more info if you need it.

kyle

Not too long ago someone said they had successfully
interfaced CBL's and photogates. Could whoever it was send
me information on this?

Thanks,

Beth

thackerb@gvsu.edu

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