Capacitors: find he charge for the new battery

  • Thread starter Alice7979
  • Start date
  • #1
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Homework Statement


A capacitor stores 7.9 x 10-2 C of charge when connected to a 6.0-V battery. How much charge does the capacitor store when connected to a 9.0-V battery?

Homework Equations


PE=CQ/2

The Attempt at a Solution


QV^2=CQ^2
(7.9 x 10-2)(6)/2 = Q(9)
C= .05 C
 

Answers and Replies

  • #2
821
192
You are looking for an equation that relates capacitance, charge held on the plates, and the voltage across the plates.
1. Solve for capacitance.
2. Rearrange the equation and solve for charge.
 
  • #4
36
2
I guess I made that more complicated
 
  • #5
821
192
If you want to post the answer you came up with, I will see if it matches mine.
 
  • #7
821
192
That's what I got. The precision of the given data is 2 significant figures, so I rounded to 0.12 C.
 

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