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Question 4.13: A parallel L–C circuit is to be resonant at a frequency of 4......

A parallel L–C circuit is to be resonant at a frequency of 400 Hz. If a 100 mH inductor is available, determine the value of capacitance required.

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Re-arranging the formula

f  =  \frac{1}{2\pi \sqrt{LC}}

to make C the subject gives:

C  =  \frac{1}{f_0^2(2\pi)^2L}

Thus

C={\frac{1}{400^{2}\times39.4\times100\times10^{-3}}}=1.58\times10^{-6}=1.58\mu F

This value can be made from preferred values using a 2.2 μF capacitor connected in series with a 5.6 μF capacitor.

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