What does complex conjugate mean in maximum power transfer?

[agabrielauto]

"the theoretical max power transfer occurs when the impedance of the load is the complex conjugate of the impedance of the source".

Can someone help me giving me a more detail explanation of this. Especialy the worlds "complex conjugate".

 

[negitron]

It's the Maximum Power Transfer theorem. Basically, it says that maximum transfer of power between load and source occurs when the impedances are equal and the imaginary part of the complex impedance is opposite in sign. In a nutshell, that means that if the load tends toward inductive, then the source should tend toward capacitive while having the same impedance.