Making a fomula to calculate the max power (electricity)

[Tqooa Ez]

Homework Statement

Show how you can make a mathematic formula for maximum power, by using the other formulas.
I think, that U is maybe called V in English.

Homework Equations

U= R*I
U_p = -r_i *I+U₀

The Attempt at a Solution

[/B]
P=I·(-r_i·I+U₀)P= -r_i·I²+U₀ I

 

[gneill]

Hi Tqooa Ez,

Welcome to Physics Forums!

Homework Statement

Show how you can make a mathematic formula for maximum power, by using the other formulas.
I think, that U is maybe called V in English.

Homework Equations

U= R*I
U_p = -r_i *I+U₀

The Attempt at a Solution

[/B]
P=I·(-r_i·I+U₀)P= -r_i·I²+U₀ I

Can you give some more context to the problem? Is there a particular circuit involved? (I'm assuming that this is a circuit analysis problem given the names of the variables that you've mentioned). A circuit diagram would be welcomed.