A defibrillator used to restore normal heart rhythm consistsessentially of a capacitor, a high voltage supply used to chargethe capacitor, and a pair of paddles (electrodes) placed on thepatient's chest. The charged capacitor is discharged in a shorttime through the patient's body. (Thisis an oversimplified version of the real instrument. In a realinstrument not all of the energy stored in the capacitor isdelivered to the patient's body.) Suppose theresistance of the body is 3000 . A 10 F capacitor is connected to a 10000 V supply.
Explanation / Answer
(a) the initial energy stored in the capacitor E=1/2*V2*C=500 J (b) the maximum current in the patient's body I=V/R=10000/3000=3.33 A (c)the time constant of the body-capacitor system T=R*C=0.03 s