G2 Gas Fitter Practice Exam

What is formed around a wire when electrical current flows through it?

1. A heat shield

2. A magnetic field

3. Static electricity

4. A plasma field

The correct answer is: A magnetic field

When electrical current flows through a wire, it generates a magnetic field around it, a phenomenon described by Ampère's circuital law. This effect occurs due to the movement of charged particles (electrons) through the conductor. The strength and orientation of the magnetic field depend on the amount of current and the configuration of the wire, such as whether it is coiled or straight. The magnetic field is integral to many applications, including electromagnets, inductors, and transformers, which capitalize on this principle to function effectively. The magnetic field lines generated are circular and centered around the wire, indicating the direction of the magnetic field at any point. In contrast, a heat shield is irrelevant in this context, as it serves to protect objects from extreme heat rather than relate to current flow. Static electricity involves a build-up of electric charge on the surface of objects, not current flow through a conductor. A plasma field refers to a state of matter where gases are ionized and does not apply to the conduction of electricity in standard wires.