Advanced Qualification · A-001 Advanced theory · A-001-001-005

What is meant by "back EMF"?

1. A A voltage that opposes the applied EMF
2. B A current that opposes the applied EMF
3. C An opposing EMF equal to R times C percent of the applied EMF
4. D A current equal to the applied EMF

Correct answer: A — A voltage that opposes the applied EMF. From the official ISED question bank, verified word for word.

Why

Back EMF is a voltage generated inside a motor or coil that pushes against the voltage you applied to start it. The full explanation — and one for every question — is in Pro.

Practise this section

Advanced theory: time constants, reactance, impedance, resonance, Q, and the mathematics behind tuned circuits.

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