A change in the magnetic field surrounding a conductor induces a voltage in the conductor. What is this induced voltage known as?

The induced voltage resulting from a change in the magnetic field surrounding a conductor is called electromotive force (EMF). This phenomenon is governed by Faraday’s Law of Electromagnetic Induction, which states that a change in magnetic flux through a circuit induces an electromotive force in that circuit. The term "electromotive force" refers broadly to the voltage generated due to electromagnetic induction.

Counter EMF, on the other hand, is specifically the voltage produced in opposition to the change in current in an inductive circuit. While it is related to induction, it is more specific to the behavior of inductors resisting changes in current rather than the general phenomenon of induced voltage from changing magnetic fields.

Inductive reactance refers to the opposition that an inductor presents to alternating current, which is caused by its inductance. This concept does not directly relate to the induced voltage in a conductor due to a changing magnetic field.

Capacitance is the ability of a system to store charge per unit voltage, and while it deals with electrical energy storage, it is unrelated to the process of voltage induction from a magnetic field.

In summary, while counter EMF is indeed a relevant term, the correct designation for the induced voltage caused by the changing magnetic field