Which of the following best explains how a magnet can be used to produce an electric current in a wire loop?

• A. By shining light on the magnet, photons transfer energy to the wire loop and create an electric current.
• B. By moving the magnet relative to the wire loop, the changing magnetic field induces an electric current according to $Faraday$'s law.
• C. By placing a stationary magnet near a stationary wire loop, a constant magnetic field will generate a continuous electric current.
• D. By heating the magnet, the increased thermal energy causes electrons to flow in the wire loop.

Answer: (B)

Verified step by step guidance

1. Understand that an electric current in a wire loop can be induced by a changing magnetic environment around the loop, not by stationary conditions or external light or heat.
2. Recall Faraday's law of electromagnetic induction, which states that a changing magnetic flux through a loop induces an electromotive force (emf) in the wire.
3. Express Faraday's law mathematically as \(\mathcal{E} = -\frac{d\Phi_B}{dt}\), where \(\mathcal{E}\) is the induced emf and \(\Phi_B\) is the magnetic flux through the loop.
4. Recognize that moving the magnet relative to the wire loop changes the magnetic flux \(\Phi_B\) over time, which according to Faraday's law induces an emf and thus an electric current in the wire.
5. Conclude that the correct explanation involves relative motion between the magnet and the wire loop causing a changing magnetic field, which induces current according to Faraday's law.