The electrical signals to the heart are typically coordinated to create a wave of compression that travels across the heart to pump the blood through the heart chambers. If these signals get misaligned, the bits of the heart muscle vibrate independently and as a result do not move blood. This situation is called fibrillation and can quickly lead to death. If the situation is caught in time, passing a jolt of current through the heart can realign the electrical signals in the heart and start it beating again. The device that delivers this current is a defibrillator. At the heart of a defibrillator is a big capacitor. A battery typically takes about a half a minute to charge this capacitor. This capacitor has a capacitance of 50 uF and, when turned on, is charged by a battery to 4,000 Volts. A. How much charge (Q) is stored on each plate of the capacitor when it is fully charged and how much energy does it store? Doesthis seem like a lot or a little charge / energy? (Certainly, a lot or a little depends on the system; here, I'm just looking for you to com- pare to one or a few phenomena, e.g., your potential energy on a mountain top or the kinetic energy of a bullet, etc. ; the charge that builds up on your nger when you get shocked or that builds up on a Van de Graaff machine, etc.. The point is that it's useful to develop intuitive benchmarks or reference points for these and other physics quantities.) B. The energy in the capacitor is delivered by placing paddles on either side of the victim's heart as shown in Figure 3. The defibril- lator delivers that charge in a millisecond through the paddles, and the hope is that the shock resets the heart so it can begin beating nor- mally. The charge is delivered in a sudden pulse that lasts about 100 ms. What is the average current, I, owing through the body? Does this seem like a lot or a little current? C. If all the energy stored in the capacitor is delivered in electric current, what is the voltage difference at which the current was deliv- ered? Again, a lot or a little voltage? D. Calculate the effective resistance, R, of the path of the current through the body. And nally, a lot or a little resistance? Figure 3: Debrillator acting to jolt the heart back to life