A heart dysfunction that can cause death is ventricular

Updated on August 6, 2022

A heart dysfunction that can cause death is ventricular
fibrillation. This is an uncoordinated quivering of the heart as
opposed to regular beating. An electric shock to the chest can
cause momentary paralysis of the heart muscle, after which the
heart will sometimes start organized beating again. A defibrillator
is a device that applies a strong electric shock to the chest over
a time of a few milliseconds. The device contains a capacitor of
several microfarads, charged to several thousand volts. Electrodes
called paddles, about 8 cm across and coated with conducting paste,
are held against the chest on both sides of the heart, their
handles are insulated to prevent injury to the operator, who calls
clear and pushes a button on one paddle to discharge the capacitor
through the patients chest.

assume that the capacitor in the defibrillator is 10 uF and is
charged to 5,000 volts.

a. how much charge is stored in the capacitor before it is
b. how much energy is released when the capacitor is
c. if the capacitor completely discharges in 2.5 ms, what is the
average current delivered by the defibrillator?
d. what is the average power delivered?



Q = CV = 5000*10×10-6 = 0.05 C


Energy = 1/2 CV^2 = 1/2* 10×10-6 * (5000)^2 = 125 J


average current = average charge / average time = 0.05/2.5×10-3 =


average power = VI = 5000*20 = 10^5 Watts

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