In the circuit, E, R1 and R2 have constant values. However R has a variable value. FInd an epxression for R that results in the max power dissipation in that resistor.(adsbygoogle = window.adsbygoogle || []).push({});

so do i do this

[tex] i_{1} = i + i_{2} [/tex]

[tex] E - i_{1} R_{1} - i_{2} R_{2} = 0[/tex]

[tex] E - i_{1} R_{1} - iR = 0 [/tex]

[tex] i_{2} R_{2} - iR = 0 [/tex]

not too sure about the last one...

and the power dissipation in that resitor is given by [tex] P = i^2 R [/tex] But to find the max power dissipation do i plug that expression for i back into the above expression and then differentiate OR sub i into this

[tex] \frac{dP}{dR} = 2iR + i^2 [/tex]

i used a sample value for i and got different values for the derivative. Which is correct?

Please help!

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# Homework Help: Power in circuits

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