Calculating Energy Delivered by a Pacemaker

[Sloan650]

A pacemaker stimulates heart tissue with R of 100ohms.
Pulse amplitude is 1.2 Volts & pulse duration is 0.5ms.
Stimulates at 70bpm
Current drain = 2microamps

Calculate energy delivered to heart from pacemaker at each pulse.

i got

P=V^2/R = 0.0144

Then Energy = Power*time = 0.0144*0.5x10-3 = 7.2x10-6 J

But do i not need to take into account the current drain?

 

[jim hardy]

power P = V X I

and since I = V/R,
then
P= V X (V/R) = V^2/R

so when you did V^2/R you included current.

the 2 microamps sounds more like battery drain to me.

7.2 microjoules 70 times a minute = 8.4 microwatts
at 2 microamps dictates least 4.2 volt battery?

anything corroborate here?

 

[Sloan650]

2µA - It is current drain due to the pacemaker circuitry.

Im a bit confused, its a past exam question.

 

[Sloan650]

all the values i gave were all that was given in the question.