Match List - I with List - II.
| List - I | List - II |
| (A) \( \int_{s}\vec{B}\cdot\vec{ds} = 0 \) | (I) magnetic field lines |
| (B) Directional property of freely suspended magnet | (II) circulating ions |
| (C) Never intersect each other | (III) torque on magnetic dipole |
| (D) Magnetic field of earth | (IV) monopoles in magnetism do not exist |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → (A)-(IV), (B)-(III), (C)-(I), (D)-(II)
Each List-I entry is a basic fact of magnetism; match it with the idea that explains it.
(A) \( \int_{s}\vec{B}\cdot\vec{ds} = 0 \) — this matches (IV) monopoles in magnetism do not exist. This is Gauss's law for magnetism: the net magnetic flux through any closed surface is zero, because no isolated magnetic pole can sit inside it.
(B) Directional property of freely suspended magnet — this matches (III) torque on magnetic dipole. The earth's field exerts a torque \( \vec{\tau} = \vec{m}\times\vec{B} \) on the magnet, which turns it until it lies along the field, roughly north-south.
(C) Never intersect each other — this matches (I) magnetic field lines. The field has one direction at each point; two lines crossing would give two directions there.
(D) Magnetic field of earth — this matches (II) circulating ions. The earth's field is thought to come from electric currents of moving charged fluid (molten iron and nickel) in the outer core, the dynamo effect.
NCERT (2026-27):
Magnetism and Gauss’s Law – “… The difference between the Gauss’s law of magnetism and that for electrostatics is a reflection of the fact that isolated magnetic poles (also called monopoles) are not known to exist. … Thus, Gauss’s law for magnetism is: The net magnetic flux through any closed surface is zero.”
The Magnetic Field Lines – “(iv) The magnetic field lines do not intersect, for if they did, the direction of the magnetic field would not be unique at the point of intersection.”