Well, let's just take this last round:What do u need to know?
What is the point of this statement? Is it an assertion? Is it a question? Is it a given condition for a problem? What?The output of a dc to ac invertor has harmonics going to a non linear load.
Is this claiming that there is always something special about the 7th harmonic? Or only DC to AC inverters? Or only for the particular inverter in this problem? What?The 7th harmonic is the most important one why?
Important in what way? Are you asking what is so special about the 7th harmonic? In terms of particularly bad things that it causes? In terms of information it tells you? What?
Again, is this a statement? Is this a question? Is this a claim that the AC waveform on the output of any inverter looks this way? Is it a statement that these hairs are the harmonics? What?The ac waveform on the output of the invertor looks fussy or has fine hairs on the ac sine waveform these are the harmonics.
While I have no idea what your point is with this question, I can at least answer it with a firm, "Yes."Non linear loads have harmonics?