Charge on capacitor

  • Thread starter Leeoku
  • Start date
  • #1
18
0

Homework Statement


I got question 10 and need help on 11
[PLAIN]http://lulzimg.com/i23/abf9f8.jpg [Broken]


Homework Equations


C = Q/V


The Attempt at a Solution


At first i thought it was a simple c = q/v and solve for Q but that wasnt right. Is that because the circuit splits off in two parts and a different number of charge is passed through each end based on the capacitors there?

This makes me think, if we use C = q/v, we would use the answer from question 10 to find the total charge available. Charge must be conserved so we take a percentage C_a is in comparison to the rest.. thats wrong too

Edit: I think i got the right answer but I need to double check on reasoning.
Using the idea that charge is convserved, i read in book that charges on capacitors in series are equal. Thus, it is a percentage split between (C_a+C_b) and (C_c+C_d). So what i did was find the percentage the capactiance in series for top and bottom were relative to the total capacitance of the 4. Using C = q/v with total capacitance, i found the total charge, then multiplied by the percentage.
C1+c2 was 2.05e-6
C3+c4 was 1.367e-6
Total was 3.417e-6

Thus c1+c2 was about 60% of total.
C(total) = q/v
q = 2.955e-4
q * 0.6 = 1.77e-4 C
 
Last edited by a moderator:

Answers and Replies

  • #2
ehild
Homework Helper
15,543
1,912
Ca and Cb connected in series, and the total voltage across them is V=86.5 V. What is the relation among the charges on series connected capacitors?

ehild
 
  • #3
18
0
i just edited while u posted, im guessing thats the right reasoning?
 
  • #4
ehild
Homework Helper
15,543
1,912
Yes, it is correct, but the calculation would be simpler if you used Q=Cr * V with Cr the resultant capacitance of Ca and Cb. Series capacitors have the same charge and it is the same as the charge on their resultant.

ehild
 

Related Threads on Charge on capacitor

  • Last Post
Replies
1
Views
968
  • Last Post
Replies
12
Views
4K
  • Last Post
Replies
2
Views
2K
  • Last Post
Replies
2
Views
2K
  • Last Post
Replies
10
Views
2K
  • Last Post
Replies
2
Views
2K
  • Last Post
Replies
3
Views
5K
  • Last Post
Replies
3
Views
1K
  • Last Post
Replies
15
Views
469
  • Last Post
Replies
5
Views
443
Top