What is the maximum power of the variable resistor R?

[headshrinker]

Homework Statement

(a) For the circuit below, the value of R is adjusted so that each of the two 10Ω resistors dissipates 10W. Calculate the value of the variable resistor R.

(b) What is the value of R if it is adjusted to dissipate the maximum power possible? For this value of R, determine the current through the resistor R and through each of the parallel 10Ω resistors.

Homework Equations

The Attempt at a Solution

I've done part (a) and found the value of R to be 2.5ohms. i have no idea how to do part (b). can anyone help?!

Thank you!

 

[willem2]

If you know what R is, what is the power dissipated in this resistor? (as a function of R)
do you know any method for finding the maximum value of a function?

 

[headshrinker]

i have no idea! I am new to this stuff! do u know?

thanks!

 

[headshrinker]

anyone?