Exam-style question
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How does terminal potential difference differ from electromotive force (emf)?.
- A.Terminal potential difference is always greater than emf
- B.Terminal potential difference is measured when no current flows, while emf is measured when current flows
- C.Terminal potential difference accounts for internal resistance, while emf does not
- D.Terminal potential difference is the same as emf
Model answer
What a good answer should say
- Terminal potential difference accounts for internal resistance, while emf does not
Explanation
Why this works
Terminal potential difference is defined as the voltage available at the terminals of a power source when current flows, factoring in internal resistance. In contrast, emf is the total voltage supplied by the source without considering internal losses.
This distinction is crucial when analyzing circuit performance under load, as it affects how much voltage is actually usable.
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