Thursday, May 3, 2012

RC Time Constant
I had an idea.  Usually nobody does a lab with capacitors, even though students are supposed to know about them, because without automated equipment you can't measure current and voltage as a function of time.
So you could get a resistor and capacitor set with a time constant of about a second, have student set the voltmeter and ammeter next to each other and take a video while they close the switch.  Then using one of the video editing programmings you can step through the video frame by frame, that is every 0.02 seconds, and read current and voltage off the screen.  They could see the voltage across the cap increase as the current decreases and they would get too see an exponential function - which they don't get anywhere else.

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