Average current produced by pacemaker

[matt72lsu]

Homework Statement

Pacemakers designed for long-term use commonly employ a lithium-iodine battery capable of supplying 0.42 A*h of charge.
b) If the average current produced by the pacemaker is 5.6 uA what is the expected lifetime of the device?

Homework Equations

C = A/s

The Attempt at a Solution

I solved for s. s = C/A = 5.6e6A (not sure if i converted that right) / .42 = 1.33e7 s. The thing is, I'm not sure how to convert this to years. thanks for the help

 

[rl.bhat]

Life time = 0.42A*h/5.6*10^-6A =...h.

 

[dacruick]

you can't convert seconds to years? You can do one of two things. Divide by seconds in a minute, divide by minutes in an hour, divide by hours in a day, then divide by days in a year. or you could search on google, "convert seconds to years" and then find the answer that way.

 

[matt72lsu]

yeah i can but i wasn't really sure if i did the first part right and used the correct equation in the first place

 

[dacruick]

ahh okay. i have no idea either

 

[rl.bhat]

yeah i can but i wasn't really sure if i did the first part right and used the correct equation in the first place

Capacity of battery is given in Ampere-hour.
Therefore the life of the battery is given by (Ampere-hour)/ current drawn from the battery.

 

[matt72lsu]

im getting like 75000 yrs. that can't be right huh?

 

[cepheid]

You know, if you keep the charge in amp-hours, it'll make things easier, because the time you calculate will automatically be in hours. All you have to do is convert the current from microamps to amps. This is easy, because a microamp is a millionth of an amp.

current = charge/time

==> time = charge/current