- 2071 Magh · 6 marks
Faraday's laws; static and dynamic emf
Short answer
Faraday's first law: changing flux linkage induces emf. Second law: e = -N dφ/dt. Statically induced emf arises from time-varying flux with stationary conductor (e = -N dφ/dt), e.g., transformer. Dynamically induced emf arises from conductor moving through a magnetic field (e = B l v sinθ), e.g., generator.
State Faraday's Laws of electromagnetic induction. Distinguish between statically induced emf and dynamically induced emf.
Faraday's laws
- First law: whenever the flux linked with a circuit changes, an emf is induced in it. The emf exists only while the flux is changing.
- Second law: the magnitude of the induced emf equals the rate of change of flux linkage: e = −N dφ/dt (volts). The negative sign (Lenz's law) shows that the emf opposes the change causing it.
Statically and dynamically induced emf
| Basis | Statically induced emf | Dynamically induced emf |
|---|---|---|
| Cause | Flux changes with time, conductor is stationary | Conductor cuts a stationary field (or field moves past conductor) |
| Formula | e = −N dφ/dt | e = B l v sin θ |
| Sub-types | Self-induced and mutually induced | Motional emf |
| Example | Transformer windings, inductor coils | DC/AC generator armature conductors |
| Moving part | None | Conductor or magnet must move |
| Direction found by | Lenz's law | Fleming's right-hand rule |
✓ Answer checked by Claude Opus 5.5 (high effort)
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