How Is Initial Power Calculated in a Plutonium-238 Powered Pacemaker?

AI Thread Summary
To calculate the initial power supplied by 180 mg of Plutonium-238 in a pacemaker, one must consider the half-life of 90 years and the energy emitted per decay, which is 5.10 MeV. The term "initial" refers to the power output before any decay has occurred, implying that the calculation assumes 100% of the isotope is still intact. The formula for power involves determining the number of decays per second, which can be derived from the decay constant and the amount of the isotope. The conversion of energy from decays into power must be done in watts, where 1 watt equals 1 joule per second. Understanding these principles is essential for accurately calculating the initial power output.
erinec
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Homework Statement


Plutonium-238 with a half-life of 90 years, emits and alpha particle of energy 5.10 MeV. 180mg of this radioisotope is used to power a pacemaker. Calculate the initial power in mW, supplied by Plutonium-238, assuming a 100% efficiency for the conversion of decay energy into usable power.

Homework Equations


I tried using:
N = No(1/2)^(t/T), where T is the half-life
P = W/t

The Attempt at a Solution


I do not know what "time" to use in order to calculate the power. What does it mean by "initial"?
Help would be very appreciated.
 
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Initial means assuming that none of it has decayed yet
Watts are joules/second so you need to work out how many decays in the first second
 

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