What exactly are they asking in this question? Optimum power transfer

[InvalidID]

Homework Statement

What is the range of values for [RL/RTH] that provide a combination of “almost” optimum power transfer to the load at a reasonably high power-transfer efficiency?

Homework Equations

The Attempt at a Solution

What are they asking for in this question? What do they mean by optimum power transfer? We replaced the source network with the thevenin equivalent.

 

[InvalidID]

Also, I don't understand how load power and source power are not the same. They both have same voltage (V_L and I_L).

Attached is the equation for efficiency.

 

[rude man]

Also, I don't understand how load power and source power are not the same. They both have same voltage (V_L and I_L).

Attached is the equation for efficiency.

Load power and source power are the same only if the load resistance equals the source resistance.

This is a weird question indeed. "Almost"? "Reasonably high ..."?

The optimum ratio for max. power into the load is when RL/RTH = 1. RTH is fixed.
What did you get for RTH?