The figure below shows a capacitor, with capacitance C = 30.0 μF, and a resistor, with resistance R = 77.5 kΩ, connected in series to a battery, with E = 21.0 V. The circuit has a switch, which is initially open. (a) What is the circuit's time constant (in s)? s (b) After the switch is closed for one time constant, how much charge (in C) is on the capacitor? C