LC Oscillations

A charged $30 \mathrm{\mu }\mathrm{F}$ capacitor is connected to a $27 \mathrm{m}\mathrm{H}$ inductor. The angular frequency of free oscillations of the circuit is

An inductor and two capacitors are connected in the circuit as shown in figure. Initially capacitor $\mathrm{A}$ has no charge and capacitor $\mathrm{B}$ has $\mathrm{C}\mathrm{V}$ charge. Assume that the circuit has no resistance at all. At $\mathrm{t}=0,$ switch $\mathrm{S}$ is closed, then given $\left[ \mathrm{L}\mathrm{C}=\frac{2}{{\mathrm{\pi }}^2\times {10}^4}{\mathrm{s}}^2 \& \mathrm{C}\mathrm{V}=100 \mathrm{m}\mathrm{C}\right]$

An $LC$ circuit contains a $20\mathrm{ }\mathrm{m}\mathrm{H}$ inductor and a $50 \mathrm{\mu }\mathrm{F}$ capacitor with an initial charge of $10\mathrm{ }\mathrm{mC}$. The resistance of the circuit is negligible. Let the instant at which the circuit which is closed be $t=0$. At what time the energy stored is completely magnetic?