----- Original Message ----- 
From: "David thurmond" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, January 18, 2012 6:49 AM
Subject: Help With Math, Resonant Frequency for LC Circuit


> Scott,
>
> I finally got to the bottom of this problem.  Not sure how the Extra
> class manual shows you to do it, but here's how I did it:
>
> The formula is:
>
> Resonant Frequency (Hz) = 1 / (2pi * sqrt(L C)
>
> where L is in Henries and C is in Farads.  So, in your example:
>
> 1.  Convert 50 microHenries to Henries, 1 microHenry = 1 x 10^-6
> Henries, so 50 microHenries = 5.0 x 10^-5 Henries = 0.00005 Henries.
> 2.  Convert 200 picofarads to Farads.  1 picofarad = 1 x 10^-9 farads,
> so 200 picofarads = 2 x 10 ^ -7 Farads = 0.0000002 Farads..
> 3.  Now, plug into the formula:
> F = 1 / (2pi * sqrt (5 x 10^-5 times 2 x 10 ^ -7)
> = 1 / 2pi * 3.16228 x 10^-6
> =50329.1 Hz = 50.3291 KHz
>
> This checks out with the calculations on the calculator at
> http://www.wa4dsy.net/cgi-bin/fr?C=200&cunits=pF&L=50&lunits=mH&FR=&funits=mHz&CALC=Resonant+Frequency