Eddy currents always travel in which manner?

Eddy currents are induced electric currents that flow in conductive materials in response to a changing magnetic field. They always travel in closed loops, or paths, because they are generated by the electromagnetic induction process. When a changing magnetic field passes through a conductor, it induces currents that circulate within the material. This circulation forms closed paths due to the nature of conservation of energy and the displacement of electrons in response to the magnetic flux.

Within conductive materials, these currents will move around obstacles and follow the material's contours, ultimately forming loops. This behavior is crucial for many applications, such as in induction heating or electromagnetic braking, where control over the path of the eddy currents is essential for the effectiveness of the technique being employed.

The other choices do not accurately describe the nature of eddy currents. For instance, they do not occur in nonconductive materials, do not always flow radially in a symmetrical coil setup, and definitely do not travel in a gas. Understanding the closed-loop flow of eddy currents helps to clarify their behavior in various testing and engineering scenarios.