Practice question · Multiple choice
Faraday's law says a CHANGING magnetic field induces a voltage, and a steady one induces nothing. Why does the rate of change matter rather than the field's strength?
Hints
- Faraday's law relates the induced EMF to a rate of change. Of what quantity?
- A very strong magnet resting on a coil: what does it induce?
Show the answer
C. Because induction responds to how fast the flux is changing.
Why
The induced voltage tracks the rate of change of flux, not the flux: rest a powerful magnet on a coil and nothing is induced at all. It is why generators must rotate. Motion is one way to change the flux and not the only one, switching off a current in a nearby wire does it with nothing moving, which is exactly how a transformer works.
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