A capacitor C 1 of capacitance 5   μ F is charged to a potential of 30   V using a battery.…

A capacitor $C_1$ of capacitance $5 \mu \mathrm{F}$ is charged to a potential of $30 \mathrm{V}$ using a battery. The battery is then removed and the charged capacitor is connected to an uncharged capacitor $C_2$ of capacitance $10 \mu \mathrm{F}$ as shown in figure. When the switch is closed charge flows between the capacitors. At equilibrium, the charge on the capacitor $C_2$ is _____ $\mu \mathrm{C}$.