Resonance

Resonance occurs in an electric circuit at a particular resonance frequency when the impedance between the input and output of the circuit is at a minimum.

f=frac{1}{2pi sqrt{LC}}

L=frac{1}{left( 2pi f right)^2C}

C=frac{1}{left( 2pi f right)^2L}

More info: http://en.wikipedia.org/wiki/Electrical_resonance