(adsbygoogle = window.adsbygoogle || []).push({}); Resistor & power dissipated question--please help

1. The problem statement, all variables and given/known data

Load resistor R is attached to a battery with EMF E and internal resistance r. For what value of the resistance R in terms of E and r will the power dissipated by the load resistor be a maximum?

2. Relevant equations

3. The attempt at a solution

So, first utilizing Kirchoff's Loop Law:

E-Ir-IR = 0

E - I(r+R) = 0

I(r+R) = E

r + R = E/I

R= E/I - r

the answer is r, but I'm not understanding why the resistor has to have a maximum value, or how to get r.

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# Homework Help: Resistor & power dissipated question-please help

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