Which statement about lines of magnetic flux is true?

• A. They are unaffected by rotating magnets.
• B. Any magnet that can rotate can align with them.
• C. They can only exist near electric currents.
• D. They are visible lines in the air.

Answer: (B)

Magnetic flux lines visualize the direction and shape of a magnetic field. They form closed loops around a magnet, emerging from the north pole and entering the south. When a magnet is free to rotate, it experiences a magnetic torque that tends to align its dipole with the external field. In other words, the magnet will rotate until its magnetic moment points along the direction of the flux lines, reaching the lowest energy orientation. That’s why a magnet capable of rotating will align with the lines of flux.

The other statements don’t fit because rotating a magnet actually changes and realigns the field around it, so the lines aren’t “unaffected.” Flux lines don’t exist only near currents; they appear around permanent magnets as well. And the lines aren’t literally visible in air; we use visualizations like iron filings or compass needles to represent them.