An RC circuit is shown in the following diagram. Initially the capacitors are uncharged. At time t-0 the switch is closed. (a). Calculate the equivalent capacitance and equivalent resistance. (b). Draw an equivalent circuit. (c). What is the current immediately after the switch is thrown? (d). How much time is needed for the current in the circuit to reach 75% of its initial value? 6.0 F 2.0 18 V 22 2 52 210 100 2