Question:
Consider the following statements:
Statement A: Magnetic monopoles do not exist and therefore magnetic field lines form closed loops.
Statement B: A bar magnet makes an angle of \(30^\circ\) with a uniform magnetic field. If the maximum torque experienced by the magnet is \(3.464 \times 10^{-5}\,\text{Nm}\), the potential energy of the system is \(3 \times 10^{-5}\,\text{J}\).
Statement C: A superconductor is a perfect ferromagnetic material.
Consider the following statements:
Statement A: Magnetic monopoles do not exist and therefore magnetic field lines form closed loops.
Statement B: A bar magnet makes an angle of \(30^\circ\) with a uniform magnetic field. If the maximum torque experienced by the magnet is \(3.464 \times 10^{-5}\,\text{Nm}\), the potential energy of the system is \(3 \times 10^{-5}\,\text{J}\).
Statement C: A superconductor is a perfect ferromagnetic material.
Statement A: Magnetic monopoles do not exist and therefore magnetic field lines form closed loops.
Statement B: A bar magnet makes an angle of \(30^\circ\) with a uniform magnetic field. If the maximum torque experienced by the magnet is \(3.464 \times 10^{-5}\,\text{Nm}\), the potential energy of the system is \(3 \times 10^{-5}\,\text{J}\).
Statement C: A superconductor is a perfect ferromagnetic material.
Show Hint
Superconductors exhibit perfect diamagnetism, not ferromagnetism (Meissner effect is key distinction).
Updated On: Jun 20, 2026
- A, B, and C are true
- A and B are true, C is false
- A and C are true, B is false
- A, B, and C are false
Show Solution
Verified By Collegedunia
The Correct Option is B
Solution and Explanation
Step 1: Analysis of Statement A.
Magnetic monopoles have not been experimentally observed. Hence, magnetic field lines always form closed loops (no starting or ending point). Therefore, Statement A is true.
Step 2: Analysis of Statement B (Torque and potential energy).
Maximum torque on a magnetic dipole is: \[ \tau_{\max} = mB \] Given: \[ \tau_{\max} = 3.464 \times 10^{-5}\,\text{Nm} \] So, \[ mB = 3.464 \times 10^{-5} \] Potential energy of a magnetic dipole in uniform field: \[ U = -mB \cos\theta \] Magnitude of potential energy: \[ |U| = mB \cos\theta \] Given \(\theta = 30^\circ\): \[ \cos 30^\circ = \frac{\sqrt{3}}{2} \approx 0.866 \] \[ |U| = 3.464 \times 10^{-5} \times 0.866 \] \[ |U| \approx 3.0 \times 10^{-5}\,\text{J} \] Thus Statement B is true.
Step 3: Analysis of Statement C.
A superconductor is not a ferromagnetic material. Instead, it exhibits perfect diamagnetism (Meissner effect), where magnetic field is expelled from the material. Hence Statement C is false.
Step 4: Final evaluation.
\[ \text{A = True, B = True, C = False} \]
Step 5: Logical conclusion.
The correct combination is: \[ \boxed{\text{A and B are true, C is false}} \]
Magnetic monopoles have not been experimentally observed. Hence, magnetic field lines always form closed loops (no starting or ending point). Therefore, Statement A is true.
Step 2: Analysis of Statement B (Torque and potential energy).
Maximum torque on a magnetic dipole is: \[ \tau_{\max} = mB \] Given: \[ \tau_{\max} = 3.464 \times 10^{-5}\,\text{Nm} \] So, \[ mB = 3.464 \times 10^{-5} \] Potential energy of a magnetic dipole in uniform field: \[ U = -mB \cos\theta \] Magnitude of potential energy: \[ |U| = mB \cos\theta \] Given \(\theta = 30^\circ\): \[ \cos 30^\circ = \frac{\sqrt{3}}{2} \approx 0.866 \] \[ |U| = 3.464 \times 10^{-5} \times 0.866 \] \[ |U| \approx 3.0 \times 10^{-5}\,\text{J} \] Thus Statement B is true.
Step 3: Analysis of Statement C.
A superconductor is not a ferromagnetic material. Instead, it exhibits perfect diamagnetism (Meissner effect), where magnetic field is expelled from the material. Hence Statement C is false.
Step 4: Final evaluation.
\[ \text{A = True, B = True, C = False} \]
Step 5: Logical conclusion.
The correct combination is: \[ \boxed{\text{A and B are true, C is false}} \]
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