Maximum power transfer from a source occurs when external resistance equals:
AZero
BEqual to internal r
CTwice internal r
DHalf of internal r
Answer & Solution
Correct answer: B. Equal to internal r
Maximum power transfer theorem: when R_external = R_internal (= r), the power dissipated in the external load is maximised. At this point, efficiency is 50% (half power in load, half in internal resistance).
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