A voltage is induced in a conductor when the conductor is?

The correct answer is that a voltage is induced in a conductor when the conductor is moved through a magnetic field. This phenomenon is a fundamental principle of electromagnetism known as electromagnetic induction, which was first discovered by Michael Faraday. According to Faraday's law of induction, when a conductor (such as a wire) is exposed to a changing magnetic field or moves through a static magnetic field, an electromotive force (EMF) is generated across the conductor. This induced voltage can cause current to flow if the conductor is part of a closed circuit.

In practical applications, generators utilize this principle to convert mechanical energy into electrical energy by rotating coils within magnetic fields, thereby inducing a current. This principle is crucial for understanding the operation of various devices, including electric generators, induction motors, and transformers. The other options do not relate directly to this core principle of induced voltage through movement within a magnetic field.