Exam-style question
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In which scenario would terminal potential difference be less than the electromotive force?.
- A.When the circuit is open
- B.When there is no internal resistance
- C.When current is flowing and internal resistance is present
- D.When the power source is fully charged
Model answer
What a good answer should say
- When current is flowing and internal resistance is present
Explanation
Why this works
Terminal potential difference is defined as the voltage available at the terminals of a power source when current flows, and it is always less than the electromotive force due to internal resistance. The key difference is that internal resistance causes a voltage drop, which is only relevant when current is flowing.
This understanding is essential for accurately predicting circuit behavior.
Common mistake
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