Chapter 10, Problem 88CP

Some camera flashes use flash tubes that requite a high voltage. They obtain a high voltage by charging capacitors in parallel and then internally changing the connections of the capacitors to place diem in series. Consider a circuit that uses four AAA batteries connected in series to charge six 10-mF capacitors through an equivalent resistance of $100\Omega$ . The connections are thenswitched internally to place the capacitors in series. The capacitors discharge through a lamp with a resistance of $100\Omega$ . (a) What is the RC time constant and the initialcurrent out of the batteries while they are connected in parallel? (b) How long does it take for the capacitors to charge to 90% of the terminal voltages of the batteries? (c) What is the RC time constant and the initial current of the capacitors connected in series assuming it discharges at 90% of full charge? (d) How long does it rake the current to decrease to 10% of the initial value?