Stored energy among a capacitor arrangement

In summary: The program rounds down to the nearest integer when calculating the potential difference, which is why the potential difference is always shown as being around 33.5 V.
  • #1
Destroxia
204
7

BEFORE YOU READ THE REST: Problem (f) is the only one I need help with. Thank you! I have already confirmed all my other values as correct in my online program!

1. Homework Statement


In the figure a potential difference V = 150 V is applied across a capacitor arrangement with capacitances C1 = 14.8 µF, C2 = 4.27 µF, and C3 = 4.22 µF. What are (a) charge q3, (b) potential difference V3, and (c) stored energy U3 for capacitor 3, (d) q1, (e) V1, and (f) U1 for capacitor 1, and (g) q2, (h) V2, and (i) U2 for capacitor 2?

http://edugen.wileyplus.com/edugen/courses/crs7165/art/qb/qu/ch0/EAT_13632548498390_6123878003864797.gif

C1 = 14.8 µF
C2 = 4.27 µF
C3 = 4.22 µF
V1 = 33.5 V
V2 = 116.4 V
V3 = 150 V
q1 = 496.5 µC
q2 = 496.5 µC
q3 = 633 µC
U1 = (NO IDEA) I keep getting anywhere from .00830 to .00831 and .00832
U2 = .0289 J
U3 = .0475 J

Homework Equations



q = V*C

1/CT = 1/C1 + 1/C2 + ... + 1/Cn (for a series)

CT = C1 + C2 + ... + Cn (for parallel)

U = (1/2) q^2/C = (1/2)QV = (1/2)CV^2

The Attempt at a Solution



So basically, I have solved for everything except problem (f), which I don't understand because my values for U2 and U3 were correct.

I have tried every variation of the stored energy equation, and have tried all forms of significant figures (my program does uncertainty +/- 1 from the 3rd significant figure).

I have also wondered if maybe the fact that the electrons travel through C2 first, before reaching C1, that it may have some effect upon the stored energy of C1, and I have tried adding, subtracting, you name it, the two values.

I'm kind of stuck at this point.
 
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  • #2
Your graphic isn't showing, it's probably behind a login:password. You can take a screenshot, clip it to just the circuit, and attach that.
 
  • #3
The value of 33.5 V for capacitor 1 has a rounding issue that has a relevant impact. If you want to use this to get the energy, keep more digits. Apart from that, it looks fine, it is just a rounding issue.

(I don't see the image either, I reverse-engineered the setup based on the calculated values :D)
 
  • #4
NascentOxygen said:
Your graphic isn't showing, it's probably behind a login:password. You can take a screenshot, clip it to just the circuit, and attach that.

mfb said:
The value of 33.5 V for capacitor 1 has a rounding issue that has a relevant impact. If you want to use this to get the energy, keep more digits. Apart from that, it looks fine, it is just a rounding issue.

Sorry about that guys, I was going to change the image but it said my thread was deleted so I couldn't find it until I got mfb's notification for some reason.

Anyway, I wonder why the program didn't place my value of 33.5 V as incorrect because it is based upon significant figures?

Here is the image anyway:

9qk1sz.jpg
 
  • #5
RyanTAsher said:
(my program does uncertainty +/- 1 from the 3rd significant figure)
Probably due to this reason.
 

1. What is stored energy among a capacitor arrangement?

Stored energy among a capacitor arrangement is the potential energy that is stored in the electric field between two conductors separated by an insulating material, also known as a dielectric. This energy is stored in the form of electric charge on the conductors.

2. How is the stored energy calculated in a capacitor arrangement?

The stored energy in a capacitor arrangement can be calculated using the equation E = 1/2CV², where E is the stored energy in joules, C is the capacitance in farads, and V is the voltage between the two conductors in volts.

3. What factors affect the stored energy in a capacitor arrangement?

The stored energy in a capacitor arrangement is affected by the capacitance, voltage, and type of dielectric material used. A larger capacitance and higher voltage will result in a higher stored energy, while a higher dielectric constant of the material will also increase the stored energy.

4. How is the stored energy released in a capacitor arrangement?

The stored energy in a capacitor arrangement is released when the capacitor is connected to a circuit. The electric charge will flow from one conductor to the other, resulting in a discharge of the stored energy in the form of electrical current.

5. Can the stored energy in a capacitor arrangement be increased or decreased?

Yes, the stored energy in a capacitor arrangement can be increased by increasing the capacitance or voltage, or by using a dielectric material with a higher dielectric constant. It can be decreased by reducing the capacitance or voltage, or by using a dielectric material with a lower dielectric constant.

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