No, Phil, they ARE using farads. If you use a calculator, you'll see that the denominator should be 0.0314, which is 6.28 x 100 x 0.00005 farads. I get the same answer they get, 31.8 ohms. They ARE incorporating the correct adjustment for the "micro" part of microfarads. You must be getting turned around somewhere in your calculating.
Martin On Sep 26, 2007, at 12:04 AM, philip madsen wrote:
Please tell me I aint nuts. I don't use formula often, so though I instinctively say reactance is I forget the application for microfarads when the unit is Farad in this equation.Yet just look how this formula is applied in not one but two different websites.. . Note they correctly state for this formula, C is capacitance in farads yet substitute microfarads into the equation. Isn't their answer wrong. shouldn't there be a 10^6 on the top line.50 micro Farads = 50 x 10 to the -6th. Farads.Or am I just too old and missing something. Can a math man please check me out? I compute the answer should be 31,250 ohms. Philip.Quote,Now you can understand why it is said that the XC varies inversely with the product of the frequency and capacitance. The formula is:Where: XC is capacitive reactance in ohms, f is frequency in Hertz, C is capacitance in farads, p is 6.28 (2 X 3.1416) The following example problem illustrates the computation of X C.
-------- Martin G. Selbrede Chief Scientist Uni-Pixel Displays, Inc. 8708 Technology Forest Place, Suite 100 The Woodlands, TX 77381281-825-4500 main line (281) 825-4507 direct line (281) 825-4599 fax (512) 422-4919 cell
mselbrede@xxxxxxxxxxxxx / martin.selbrede@xxxxxxxxxxxx