Capacitor

A capacitor of capacitance \(\mathrm{C}\) and potential \(\mathrm{V}\) has energy \(\mathrm{E}\). It is connected to another capacitor of capacitance \(2 \mathrm{C}\) and potential \(2 \mathrm{~V}\). Then the loss of energy is \(\frac{x}{3} \mathrm{E}\), where \(x\) is _______.