Question

A magnetic fluid material is filled in U-shaped smooth tube as shown in Figure-l. Now pair of magnetic poles are placed at one end at point A and after some time, the new shape of fluid shown in Figure-II. The filled fluid is ______

• A. Ferromagnetic
• B. Paramagnetic
• C. Diamagnetic
• D. Ferrimagnetic

Answer 1

Answer: (C)

Diamagnetic

Answer 2

The fluid level drops in the arm where magnetic poles are placed, indicating repulsion by the magnetic field. Materials repelled by magnetic fields are diamagnetic.

• Initial State (Figure-I): The magnetic fluid in the U-shaped tube is at the same level in both arms (A and B), indicating equilibrium under gravity.

• Final State (Figure-II): When a pair of magnetic poles (N-S) are placed near one arm (at point A), the fluid level in that arm decreases, and consequently, the fluid level in the other arm (at point B) increases.

• Interpretation: A decrease in fluid level in the presence of a magnetic field indicates that the fluid is being repelled by the magnetic field.

• Magnetic Properties:

  • Paramagnetic and Ferromagnetic/Ferrimagnetic materials are attracted to magnetic fields (they move from weaker to stronger parts of the field). If the fluid were paramagnetic or ferromagnetic/ferrimagnetic, its level would rise in the presence of the magnetic poles.
  • Diamagnetic materials are repelled by magnetic fields (they move from stronger to weaker parts of the field). This behavior matches the observation in Figure-II, where the fluid is pushed away from the region of the magnetic field.

Therefore, the filled fluid is diamagnetic.