09 February 2012

Capacitors (9.2.12)

Today Oscar introduced us to capacitors.  Capacitors accumulate current and express it as voltage.  We calculate it using this formula:

A sample capacitor is shown below:


Since our circuit contains a resistor, the capacitor will charge until there is a 0 voltage difference between the ends of the resistor.  The capacitor charges faster when there is a greater voltage difference.  If we graph the voltage over time, we see the voltage starts high, but approaches 0 and stabilizes.

As you can see here, in a more detailed version of our circuit shown above, the amount of current flowing clockwise becomes smaller.


We then tried working with capacitors on our breadboards, and worked with this circuit: 


Oscar gave us a pictorial version as well, which looks like this: 


By adding a capacitor to our circuit, we made an oscillator!


We added a speaker (the cylindrical cone with the big G) so that when we manipulated the potentiometer, a different pitch came from the speaker.  The end of class was a lot of fun when we all had speakers going at various high, annoying pitches!


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