Textbook: Physics 8e, Cutnell and Johnson Chap 20 Problem 103 /solution/solution

Question

Textbook: Physics 8e, Cutnell and Johnson
Chap 20 Problem 103

/solution/solution/714716

Question:
In a pacemaker, a pulse is delivered to the heart 81 times aminute. The capacitor that controls this pulsing ratedischarges through a resistance of 1.8*10^6 ohm. One pulse isdelivered everytime the fully charged capacitor loses 63.2% of itsoriginal charge. What is the Capacitance of the Capacitor?

The equation that you suggest is   q= q_o e^(-t/RC)

t =.7404
R=1.8*10^6

So to solve I take the (ln q/q_o) and I get 1.44

So the Capacitance should equal -t/(1.8*10^6)(1.44)

The corect answer in the back of the book is 4.1*10^-7 but when Iwork out the problem I keep getting 2.86*10^-7.

Could you please check the math on this problem and let me know ifI am making a mistake or if the answer given is incorrect?

Thank you so much for your time and help!

Explanation / Answer

note "the fully charged capacitor loses63.2% of its original charge.", so q/q0 = 1 - 63.2% =0.368 now you can get the right answer.

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