\(\omega _1=\omega _2=\frac{1}{L_1C_1}=\frac{1}{L_2C_2}\Rightarrow L_1C_1=L_2C_2\)

Khi ghép nối tiếp ta có \(\left\{\begin{matrix} L_{td}=L_1+L_2\\ \frac{1}{C_{td}}=\frac{1}{C_1}+\frac{1}{C_2}\Rightarrow C_{td}=\frac{C_1C_2}{C_1+C_2} \end{matrix}\right.\)

\(L_{td}C_{td}=\frac{(L_1+L_2)C_1C_2}{C_1+C_2}=\frac{C_2(L_1C_1)+C_1(L_2C_2)}{C_1+C_2}=L_1C_1=L_2C_2\)

\(\omega =\frac{1}{\sqrt{L_{td}C_{td}}}=\omega _1=\omega _2=120\pi (rad/s)\Rightarrow f=60(Hz)\)