A pacemaker applies 72 stimulating square-pulses per minute to the heart. The pu

Question

A pacemaker applies 72 stimulating square-pulses per minute to the heart. The pulse length is 0.5 ms, and the amplitude is 5 V. Two electrodes convey the pulses from the generator to the heart wall. The resistance of the heart tissue between the connecting electrodes is 600 Ohm. a) What is the power in one pulse? b) What is the energy in one pulse? c) What is the average power of the pacemaker? d) For how many years can a pacemaker work if the total stored energy in it is initially 15 kJ, and that power supply is used with an efficiency of 35%?

Explanation / Answer

a) In for the power of each pulse ,
P = v^2/R
P = 5^2/600
P = 0.0417 W
power in one pulse is 0.0417 W
b)
In energy of each pulse = 0.0417 * 0.5 *10^-3
energy of each pulse = 2.083 *10^-5 J
c)
In for the average power
average power = total energy in 1 min/time
average power = 72 * 2.083 *10^-5/60
average power = 2.5 *10^-5 W
d)
In let the time is t
as energy = power * time
15 *10^3 * 0.35 = 2.5 *10^-5 * t
t = 2.1 *10^8 s
t = 6.659 years
the pacemaker will work for 6.659 years

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