1. Network Theorems (AC Circuits)
D C Kulshreshtha

2. Maximum Power Transfer Theorem for AC Circuits
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4. The power delivered to the load is
Phasor current and voltage are
where
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6. A little forethought saves us some work
A little forethought saves us some work. (XTh + XL) absorbs no power; any nonzero value only reduces PL. Hence we can put XL = - XTh, so as to get
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7. This expression, we have already maximized for purely resistive case, by selecting RL = RTh. Hence, we must have
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8. Exercise
Show that if the load is purely resistive in an ac circuit, the condition for maximum power transfer is
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