# Help with R C and frequency

Discussion in 'Homework Help' started by tegman, Apr 30, 2009.

1. ### tegman Thread Starter New Member

Apr 30, 2009
3
0
Im having a problem with a ? in my book.

A 47Ω load resistor is connected in series with a 10 microfared capacitor. At what freq. will the capacitor reach the same value as the load resistor?

Aron

2. ### PRS Well-Known Member

Aug 24, 2008
989
35
Xc, the impedence (resistance) of the capacitor is a function of frequency.

Xc=1/(2*pi*f*C)

Plug in 47 ohms and 10uF and solve for f.

3. ### tegman Thread Starter New Member

Apr 30, 2009
3
0
So I work it like this?

Xc=1/(2*pi*f*c)

2*pi*Xc*c=1/f

f=1/2*pi*47*10*10 -6 power

f=338.62 HZ

4. ### StayatHomeElectronics Well-Known Member

Sep 25, 2008
864
40
That's exactly the way to do it.

5. ### tegman Thread Starter New Member

Apr 30, 2009
3
0
OK. The load resistor is what was confusing me. I wasnt sure if I should sub. its 47 ohms for Xc in the formula.

Thanks a bunch,
Aron

6. ### StayatHomeElectronics Well-Known Member

Sep 25, 2008
864
40
The load resistor of 47 ohms is what you were trying to match. It does not have any frequency component to it like a capacitor or inductor so the simple substitution should work.

S@HE

Aug 24, 2008
989
35

8. ### StayatHomeElectronics Well-Known Member

Sep 25, 2008
864
40
It the state flag of Ohio.

When I was working near Pittsburgh I posted one on my wall in my office, it brought a great deal of conversation because I would never tell people what it was. No one ever guessed either.

9. ### PRS Well-Known Member

Aug 24, 2008
989
35
Well, thanks for telling me! I live in Washington state and our flag has George Washington on it, good heavens! I wish the eastern part of our state would seceed from the west and we'd adopt the name Columbia (after the river), and feature Lewis and Clark on our flag. I know ... it ain't gonna happen.

10. ### StayatHomeElectronics Well-Known Member

Sep 25, 2008
864
40
I never knew there was such division in Washington state! But, I guess we're a little off topic here.