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## Homework Statement

Why is the following situation impossible? A battery has an emf of E = 9.2V and an internal resistance of r = 1.2 ohms. A resistance R is connected across the battery and extracts from it a power of P = 21.2W.

## Homework Equations

My book gives these equations throughout the section:

[tex]\Delta[/tex]V = [tex]\epsilon[/tex] - Ir

[tex]\epsilon[/tex] = IR + Ir

I = [tex]\epsilon[/tex]/(R+r)

P=I[tex]\Delta[/tex]V

## The Attempt at a Solution

I tried plugging in some of my values into some of these formulas, but I don't know the current, so therefore any formula with I in it, I couldn't do. Can someone steer me in the correct direction somehow please?