How are magnetic fields related to electric currents?

A magnetic field is generated around a conductor when current flows is the correct understanding because of the fundamental principle discovered by Hans Christian Ørsted in 1820. When an electric current passes through a conductor, such as a wire, it produces a magnetic field that circles the conductor. This phenomenon is essential in electromagnetism and is the basis for many applications, including electric motors and transformers.

According to Ampère's law, the strength and orientation of the resulting magnetic field are determined by the direction and amount of current flowing through the wire. This magnetic field can interact with other magnetic fields and can be detected using devices like compasses or magnetic field sensors. This relationship illustrates one of the key principles of electromagnetism—that electricity and magnetism are intrinsically linked.

The other options misrepresent the relationship between magnetic fields and electric currents. Static conditions do not generate a magnetic field; it is the movement of charge (current) that does so. Additionally, magnetic fields are indeed related to electric currents, as demonstrated by how they are produced. Finally, while magnetic and electric fields can be considered opposite in certain contexts (like their respective forces), the statement does not correctly describe their relationship with current flow.