# 2 Capacitors in Parallel

1. Mar 2, 2009

### phys62

1. The problem statement, all variables and given/known data
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.

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

3. 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!!!

2. Mar 2, 2009

### Delphi51

Looks okay to me!

3. Mar 2, 2009

### phys62

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. Mar 2, 2009

### Delphi51

micro means 10^-6
.625 uF = .625 x 10^-6 F = 6.25 x 10^-7 F

5. Mar 2, 2009

### phys62

Whew, dumb mistake on my part. Thanks!