Calculating Capacitance in Parallel Circuits with AC Generator

In summary, two identical capacitors are connected in parallel to an ac generator with a frequency of 660 Hz and a voltage of 27 V, resulting in a current of 0.14 A. Using the equation Z = x of c = V/I, the impedance is calculated to be 192.86 ohms. Using the formula x of c = 1/(2pi*fc), the capacitance for each capacitor is found to be 1.25 uF. When converted to units of F, this is equivalent to 6.25x10^-7 F. The correct answer is .625 uF or 6.25x10^-7 F.
  • #1
phys62
53
0

Homework Statement


Two identical capacitors are connected in parallel to an ac generator that has a frequency of 660 Hz and produces a voltage of 27 V. The current in the circuit is 0.14 A. What is the capacitance of each capacitor? Note: The ac current and voltage are rms values and power is an average value unless indicated otherwise.


Homework Equations


Z = x of c = V/I
x of c = 1/(2pi*fc)


The Attempt at a Solution



x of c = 27V /.14A = 192.86 ohms

192.86 ohms = 1 / (2pi*fc) = 1 / (6.28*(660)c) = 1/(4144.8 x c)
c=1.25 uF

1.25uF equals the capacitance of the two identical capacitors connected in parallel.
The capacitance of each capacitor equals 1.2uF/2 = .625 uF

This answer is incorrect, but I have absolutely no idea what I'm doing wrong.. Thanks for any help!
 
Physics news on Phys.org
  • #2
Looks okay to me!
 
  • #3
They're asking me to submit my answer in units of F, and I think I may just have my decimal point in the wrong place... (I submitted .625 F). And now I'm confusing myself a lot as to where the decimal place really should be. Should my final answer actually be 6.25x10^-13 F?

6.25x10^-7 uF x (1x10^-6 F / 1 uF) = 6.25x10^-13 F ?
 
  • #4
micro means 10^-6
.625 uF = .625 x 10^-6 F = 6.25 x 10^-7 F
 
  • #5
Whew, dumb mistake on my part. Thanks!
 

1. What is the total capacitance of two capacitors in parallel?

The total capacitance of two capacitors in parallel is equal to the sum of their individual capacitances. This is because when capacitors are connected in parallel, the effective plate area increases, resulting in a higher overall capacitance. Mathematically, the equation for total capacitance in parallel is CT = C1 + C2.

2. How does the voltage differ in a parallel circuit with two capacitors?

In a parallel circuit with two capacitors, the voltage across each capacitor is the same. This is because capacitors in parallel have the same potential difference across them, as they are connected to the same voltage source. This also means that the voltage across the parallel combination is equal to the voltage of the source.

3. Can two capacitors in parallel have different capacitances?

Yes, two capacitors in parallel can have different capacitances. The total capacitance in parallel is dependent on the individual capacitances of each capacitor, so they can have different values. However, it is important to note that the final capacitance value will always be higher than the individual capacitances.

4. What happens to the total charge in a parallel circuit with two capacitors?

In a parallel circuit with two capacitors, the total charge is split between the two capacitors. This is because the capacitors are connected in parallel, allowing for the flow of electric charge between them. The total charge remains the same, but the distribution of charge is different between the capacitors.

5. How does the energy stored in capacitors in parallel compare to a single capacitor?

The energy stored in capacitors in parallel is higher than the energy stored in a single capacitor. This is because the total capacitance in parallel is greater than the capacitance of a single capacitor, resulting in a higher amount of energy being stored. The energy stored in parallel capacitors is also distributed between the two capacitors.

Similar threads

  • Introductory Physics Homework Help
Replies
2
Views
821
  • Introductory Physics Homework Help
Replies
4
Views
1K
  • Introductory Physics Homework Help
Replies
5
Views
895
  • Introductory Physics Homework Help
Replies
3
Views
928
  • Introductory Physics Homework Help
Replies
3
Views
1K
  • Introductory Physics Homework Help
Replies
28
Views
2K
  • Introductory Physics Homework Help
Replies
3
Views
2K
  • Introductory Physics Homework Help
Replies
3
Views
1K
  • Introductory Physics Homework Help
Replies
3
Views
1K
  • Introductory Physics Homework Help
Replies
1
Views
1K
Back
Top