I keep getting “EMF and terminal voltage” questions wrong in Current Electricity. What's the trap?
assuming terminal voltage equals EMF even when current flows.
The usual trap: assuming terminal voltage equals EMF even when current flows. How to avoid it: terminal V = EMF − I·r, so it drops under load. Go back to the definition — EMF is the battery's full push; terminal voltage is what's left after the internal resistance drops some of it.
Key point
EMF and terminal voltage
Common mistake
assuming terminal voltage equals EMF even when current flows.
Memory tip
terminal V = EMF − I·r, so it drops under load.
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