This circuit demonstrates why a capacitor passes current on AC and NOT DC. Throw the switch and leave it. The capacitor will charge and only draw current while it's first charging. One it's charged. It will stay charged and the voltage will cancel out the battery voltage and the current will be zero. If you move the switch back and forth the current will be constantly alternating between the two voltage sources. This will cause the capacitor to be constantly charging in one direction then changing in the other direction which will be a constant flow of current. This demonstrates why a capacitor in a series circuit passes AC and NOT DC.
