We're asked to maximize voltage across the resistor RL, then do the same for current and power. But to find a value of R that maximizes VL, I think we'd just say infinity. And to maximize current through the resistor RL, would it not be for RL = 0? But then how do you find a value of RL that maximizes power delivered to RL?

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  • $\begingroup$ Are you familiar with the maximum power transfer theorem? $\endgroup$
    – Bob D
    Oct 25, 2019 at 8:18
  • $\begingroup$ Enter maximum power transfer into this site's search engine to reveal many answers to your question. $\endgroup$
    – Farcher
    Oct 25, 2019 at 8:33
  • $\begingroup$ Also, would I be correct in assuming that your only option is to alter $R_L$? $\endgroup$
    – Bob D
    Oct 25, 2019 at 8:35
  • $\begingroup$ It is unclear what is the variable that is being maximized. In the text you say "find a value of R that maximizes ..." but there is no R in the diagram, just RL and Rs. Please update the question to clarify $\endgroup$
    – Dale
    Apr 12 at 18:08

1 Answer 1


Well, we know that the power through a resistor is given by:


Ohm's law, states:


In your circuit, we know that the voltage across the load resistor is given by:


The current in the circuit is given by:


So, the power in the resistor $\text{R}_\text{L}$ is given by:


In order to calculate $\text{R}_\text{L}$ to find the maximum, we find:


Then we get:



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