$n=n_1=\dfrac{30v}{s} \rightarrow R=Z_{C_1} \rightarrow \omega _1.R.C=1$
$n=n_2: U_C=\dfrac{\dfrac{\Phi}{\sqrt2}.\omega .\dfrac{1}{\omega .C}}{\sqrt{\left(Z_L-Z_C\right)^2+R^2}}=\dfrac{\dfrac{\Phi}{\sqrt2}.\dfrac{1}{C} }{\sqrt{\left(Z_L-Z_C\right)^2+R^2}} $
$U_{C_{max}} \Leftrightarrow...