A defibrillator provides an electric shock to a heart to restore its normal rhythm. The energy to do this is 125 J, at a steady voltage of 500 V, for a time of 10 milliseconds. What is the current during this process?

Answer:

19) D

Power = Energy/time

Time = 10 milliseconds = 0.01 seconds
Energy = 125J

Power = 125/0.01 = 12500 Watts

We know the voltage = 500V and that Power = Current x voltage
Current = Power ÷ Voltage
Current = 12500 ÷ 500 = 25 A