The Resonant Frequency $f _ { r }$ ) of a Circuit Containing Both Inductance ( L )

The resonant frequency ( $f _ { r }$ ) of a circuit containing both inductance ( L ) and capacitance ( C ) may be found by the reciprocal of two pi ( $2 \pi$ ) Hint:((The reciprocal is 1/ $2 \pi$ ) ) multiplied by the square root of the product of the inductance and capacitance.

A) $f _ { r } = \sqrt { L C } / 2 \pi$
B) $f _ { r } = 1 / 2 \pi \sqrt { L C }$
C) $f _ { r } = L / 2 \pi \sqrt { L C }$
D) $f _ { r } = C / 2 \pi \sqrt { L C }$