The resonant frequency of an LC circuit with $L = 100\,\text{mH}$ and $C = 1\,\mu\text{F}$ is closest to

1. Resonance: $f_0 = \dfrac{1}{2\pi\sqrt{LC}}$. 2. $L = 100\,\text{mH} = 0.1\,\text{H}$; $C = 1\,\mu\text{F} = 10^{-6}\,\text{F}$. 3. $LC = 0.1 \times 10^{-6} = 10^{-7}$. 4. $\sqrt{LC} = \sqrt{10^{-7}} = 3.162\times 10^{-4}\,\text{s}$. 5. $f_0 = 1/(2\pi \cdot 3.162\times 10^{-4}) = 1/(1.987\times 10^{-3}) = 503.3\,\text{Hz}$. 6. Other options are off by orders of magnitude or wrong calculations. _Source: Tony Kuphaldt, "Lessons in Electric Circuits — AC", Vol II, Ch 6 (Resonance numerical)._