1) An implanted pacemaker supplies the heart with 72 pulses per minute, each pul

Question

1) An implanted pacemaker supplies the heart with 72 pulses per minute, each pulse providing 3.0 V for 0.95 ms. The resistance of the heart muscle between the pacemaker's electrodes is 600 ohms.

a) Find the current that flows during a pulse.

b) Find the energy delivered in 1 pulse
c) The average power supplied by the pacemaker

2) Use the following circuit:

a) use Kirchoff's laws to write 3 independent equations relating the currents (as drawn), resistances, and the emf values in the circuit.

b) If E1 = 3V, E2 = 8 V and R1 = 2 ohms, R2 = 4 ohms, R3 = 8 ohms, solve for the 3 currents.

to write 3 independent equations relating the cur emf values in the circuit. V, and R1=2 Omega, R2 = 4 Omega, R3 = 8 Omega, solve for the

Explanation / Answer

1) current = V/r = 3/600 = 0.005 amp

   power = V*V/r = 3*3/600 = 0.015 Watt

    energy = power * time = 0.015* 0.95 * 0.001 = 0.00001425 joules

2) a)

              I1 + I3 = I2          -(1)

              R1*I1 + R2*I2 = 11

              2 * I1 + 4 * I2 = 11    -(2)

            R2 * I2 + R3 * I3 = 8

           I2 + 2 * I3 = 2        -(3)

   b) On solving we have

              2 * I1 + 4 * I2 = 11           -(2)

            and 3 * I2 - 2 * I1 = 2   -(3)         (on putting I3 = I2 - I1)

         on adding them we have 7 * I2 = 13 or I2 = 13/7 = 1.85

       I1 = 25/14 = 1.75

     I3 = 1/14 = 0.071

              

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