(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A resistor with resistance R is connected to a battery that has emf 12.0 V and internal resistance r=0.40 ohms. For what two values of R will the power dissipated in the resistor be 80.0 W?

P=80 W

r=0.40 ohms

EMF=12V

Find R

2. Relevant equations

P=VI, = I^2R = V^2/R

V= EMF - Ir

V=IR

3. The attempt at a solution

I need to find resistance R of the resistor. But I can't seem to find the current I, which I need to find V, so that I can find R. I have tried rearranging the equations all manner of ways and can't seem to figure it out.

The other issue is how the question asks to find the two values of R. I assume that for there to be two values that somehow R has to be squared so that you have the same number, just positive and negative. That is my best guess at the moment.

Thanks for the help.

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# Homework Help: Calculating Resistance in a Circuit

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