Xc = 1/2 pie fC

• Dec 1st 2006, 05:15 PM
turbod15b
Xc = 1/2 pie fC
Xc = _1_
piefC

Capacitive Reactance (Xc) in Ohms
Frequency (f) in Hz
Capacitance (C) in Farads in a electrical circuit
Taking 2pie as equal to 6.284

a) how i make 'f' the subject?

b) how do i calculate f when Xc = 318.47 Ohms, C = 1uF (equivalent to 1x10exp-6F)

im really stuck :(
• Dec 1st 2006, 05:28 PM
topsquark
Quote:

Originally Posted by turbod15b
Xc = _1_
piefC

Capacitive Reactance (Xc) in Ohms
Frequency (f) in Hz
Capacitance (C) in Farads in a electrical circuit
Taking 2pie as equal to 6.284

a) how i make 'f' the subject?

b) how do i calculate f when Xc = 318.47 Ohms, C = 1uF (equivalent to 1x10exp-6F)

im really stuck :(

The Greek letter $\pi$ is spelled "pi" not "pie."

a) $X_C = \frac{1}{2 \pi fC}$

$2 \pi C X_C = \frac{1}{f}$

Now invert the fraction:
$f = \frac{1}{2 \pi C X_C}$

b) $f = \frac{1}{2 \pi \cdot 1 \times 10^{-6} \, F \cdot 318.47 \, \Omega} = 49.9749 \, Hz$

-Dan
• Dec 2nd 2006, 05:38 AM
turbod15b
thank you