Match List-I with List-II
| List-I | List-II |
| Parameter of Magnetic Dipole | Formula |
| (A) Magnetic moment | (I) \( \mu_0\,2\mathbf{m}/(4\pi x^{3}) \) |
| (B) Magnetic field on the equatorial line | (II) \( \mathbf{m}\times\mathbf{B} \) |
| (C) Magnetic field on axial line | (III) \( I\mathbf{A} \) |
| (D) External torque in magnetic field | (IV) \( \mu_0\,\mathbf{m}/(4\pi x^{3}) \) |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → (A) - (III), (B) - (IV), (C) - (I), (D) - (II)
A magnetic dipole behaves like a current loop: its moment, its fields on the axis and the equator, and the torque on it all have standard forms.
(A) Magnetic moment — this matches (III) \( I\mathbf{A} \). The moment of a current loop is the current times the area vector.
(B) Magnetic field on the equatorial line — this matches (IV) \( \mu_0\,\mathbf{m}/(4\pi x^{3}) \). On the equator of a short dipole the field is half the axial value and points opposite to the moment.
(C) Magnetic field on axial line — this matches (I) \( \mu_0\,2\mathbf{m}/(4\pi x^{3}) \). On the axis the field is twice the equatorial value and points along the moment.
(D) External torque in magnetic field — this matches (II) \( \mathbf{m}\times\mathbf{B} \). The torque on a dipole in a field \( \mathbf{B} \) is \( \tau = mB\sin\theta \), in vector form \( \mathbf{m}\times\mathbf{B} \).
NCERT (2026-27):
The Electrostatic Analog – …
