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Homework Help: Inductance Question

  1. Mar 23, 2005 #1
    Hi all, I've managed to solve the following question but the answer I'm getting doesn't seem right...

    What inductance must be connected to a 17 pF capacitor in an oscillator capable of generating 550 nm (i.e. visible) electromagnetic waves? Comment on your answer.

    To solve it I just rearranged the following equation and isolated L

    [tex]f=\frac{1}{2\pi\sqrt{LC}}[/tex]

    I'm also not sure what the prefix 'p' in the 17pF stands for...

    Thanks
     
    Last edited: Mar 23, 2005
  2. jcsd
  3. Mar 23, 2005 #2
    p stands for pico, which is equivalent to 10^(-12).
     
  4. Mar 23, 2005 #3
    So this is what I have now, the answer I'm getting is extremly small, could someone please just check over my work to see if I have made any errors... Thanks

    [tex]
    \begin{gather*}
    C=17pF=1.7\times10^{-11}F\\
    \lambda=550nm=5.5\times10^{-7}m\\
    c=3.0\times10^8m/s
    \end{gather8}
    [/tex]

    [tex]
    \begin{gather*}
    f=\frac{1}{2\pi\sqrt{LC}\\
    \frac{c}{\lambda}\sqrt{LC}=\frac{1}{2\pi}}\\
    LC=(\frac{\lambda}{2c\pi})^2\\
    L=(\frac{\lambda}{2c\pi})^{2}(\frac{1}{C})\\
    L=5.0\times10^{-21}\\
    \end{gather*}
    [/tex]
     
  5. Mar 23, 2005 #4
    Your algebra looks right to me. I don't remember much about inductance to comment on the physics of it.
     
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