In electrical theory, what are flux lines associated with?

Flux lines are primarily associated with magnetic fields. These lines, often visualized as field lines, represent the direction and strength of a magnetic field in space. The density of these lines indicates the strength of the magnetic field, while the direction of the lines shows the orientation of the magnetic force. In electromagnetism, magnetic flux lines are crucial for understanding how magnetic fields interact with electric currents and magnetic materials.

For the other options: Electric current flow is more directly associated with electric field lines rather than magnetic flux lines. Voltage levels relate to the electric potential difference and do not have a direct correlation with the concept of flux lines. Capacitance effects involve electric fields and charges in capacitors, not magnetic fields represented by flux lines. Thus, the association of flux lines with magnetic fields is the only option that accurately reflects their definition and significance in electrical theory.