# A couple circuit problems

1. Jan 30, 2005

### triplezero24

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.

Last edited by a moderator: May 1, 2017
2. Jan 30, 2005

### triplezero24

3. Jan 31, 2005

### learningphysics

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. Jan 31, 2005

### triplezero24

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!

Last edited by a moderator: May 1, 2017
5. Jan 31, 2005

### learningphysics

6. Jan 31, 2005

### triplezero24

I'll attatch it.

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7. Jan 31, 2005

### learningphysics

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. Jan 31, 2005

### triplezero24

Sorry. It says point A is grounded (V=0).

9. Jan 31, 2005

### learningphysics

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!