Match List-I with List-II
| List-I | List-II | ||
| Physical Quantity | Unit | ||
| (A) | Magnetic Moment | (I) | \( \mathrm{N\,A^{-2}} \) |
| (B) | Magnetic field strength | (II) | \( \mathrm{N\,m\,rad^{-1}} \) |
| (C) | Torsion Constant | (III) | \( \mathrm{A\,m^{-1}} \) |
| (D) | Magnetic permeability | (IV) | \( \mathrm{A\,m^{2}} \) |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → (A) - (IV), (B) - (III), (C) - (II), (D) - (I)
Each unit follows from the defining relation of the quantity.
(A) Magnetic Moment — this matches (IV) \( \mathrm{A\,m^{2}} \). The moment of a current loop is \( m = IA \), current times area.
(B) Magnetic field strength — this matches (III) \( \mathrm{A\,m^{-1}} \). For a solenoid \( H = nI \), the number of turns per metre times the current.
(C) Torsion Constant — this matches (II) \( \mathrm{N\,m\,rad^{-1}} \). The restoring torque is \( \tau = k\theta \), so \( k \) is torque per radian.
(D) Magnetic permeability — this matches (I) \( \mathrm{N\,A^{-2}} \). From the force per unit length between two parallel currents, \( \mu_0 = 2\pi d\,F/(I_1 I_2 L) \), the unit is \( \mathrm{N\,m^{-1} \times m\,A^{-2}} = \mathrm{N\,A^{-2}} \).
NCERT (2026-27):
Summary – …
