**A**, **B** and **C** with capacitances $C_0,$ $2C_0$ and $2C_0,$ respectively. The voltage of the power supply is constant. Let $E_1$ be the electric energy charged on capacitor **A** when the switch **S** is open. Let $E_2$ be the electric energy charged on capacitor **A** when the switch **S** is closed. Then what is the ratio $E_1:E_2?$