Answer: Lenz's law.
- A Lenz's law
- B Ohm's law
- C Coulomb's law
- D Boyle's law
Correct answer: A. Lenz's law
Explanation: Lenz's law expresses the opposition, reflected in the minus sign of Faraday's law.
As a magnet approaches a coil, flux rises steadily and a constant non-zero EMF is induced (Faraday's law). Once the magnet stops moving, flux stays constant and the induced EMF drops to zero - EMF only exists while flux is actively changing.
Concept context
Faraday's and Lenz's laws, motional EMF, self/mutual inductance, eddy currents, and the AC generator - how a changing magnetic flux creates an electric current.