Advanced Qualification · A-001 Advanced theory · A-001-001-005
What is meant by "back EMF"?
- AA voltage that opposes the applied EMF
- BA current that opposes the applied EMF
- CAn opposing EMF equal to R times C percent of the applied EMF
- DA 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 is section A-001 of the Advanced exam: Advanced theory: time constants, reactance, impedance, resonance, Q, and the mathematics behind tuned circuits.
Drill A-001 — free, no account