A couple circuit problems

  • #1
1. For http://www.pen.eiu.edu/~cuemc4/circuit.bmp [Broken] picture.. Calculate the potential at point D.

2. I 15-V battery is connected to three capacitors in series. The capacitors have the following capacitances: 4.5microFarads, 12.0microFarads, and 32microFarads. Find the voltage across the 32microFarad capacitor.

I am so lost. :frown:
 
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Answers and Replies

  • #2
Please? I'm desperate!
 
  • #3
learningphysics
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I couldn't open your first picture... I get a "server not found" message.

For the second one... first find the equivalent total capacitance (combine 3 capacitors in series). The find the total charge on this equivalent capacitor.

You should then be able to get the charge on each capacitor (hint: this is really simple... if you are unsure read your textbook regarding combining series and parallel capacitors), and then get the voltage on each capacitor.
 
  • #4
http://www.pen.eiu.edu/~cuemc4/circuit.bmp [Broken]

That might work. Mak sure you're soomed in all the way or it wont look right. Thanks for the help so far!
 
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  • #5
learningphysics
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New link doesn't work either.
 
  • #6
I'll attatch it.
 

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  • #7
learningphysics
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Hmmm... absolute potential can't be calculated unless there's ground assigned somewhere. But I don't see one on the circuit. Are you sure the question asks for potential at D and not potential difference between 2 different points? Does the question mention about 0 volts being assigned somehwere?
 
  • #8
Sorry. It says point A is grounded (V=0).
 
  • #9
learningphysics
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ok cool. So first find the current I in the circuit using KVL. So then you can get all the voltage drops across all the resistors (voltage drop across a resistor=current*resistance). Using that you should be able to find the potential at D. Be careful with signs!!

Hope this helps!
 

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