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Question #95564
The Question
A long cylindrical paramagnetic core is placed in an environment at absolute zero temperature (). The core is subjected to a superposed external magnetic field intensity , where is a positive constant in . Assume the material is highly paramagnetic such that its susceptibility obeys Curie's Law (where is the Curie constant in ), allowing the approximation for the magnetic field inside the core to be . The time-varying component of the magnetic field induces eddy currents, resulting in a time-averaged power dissipation per unit volume given by , where is the root-mean-square value of the AC component of the magnetic field inside the core, and is a constant in . The core dissipates heat to its surroundings at a rate per unit volume given by , where is a constant in and is the steady-state absolute temperature of the core. Assuming uniform temperature distribution, what is the total root-mean-square magnetic field inside the core in the steady state?
Options
- A.
- B.
- C.
- D.
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Multi-Concept_Bridge
Master problems that require linking physics and math concepts to solve complex competitive questions.
Concepts Behind This Question
Superposition of Magnetic Fields|Curie’s Law|Dynamic Resistance (AC Resistance)
Why This Question Is Tricky
Examiner Levers
Dimensional Analysis
Tests if the student verifies units/dimensions before selecting.
Difficulty Boost : +2Common Mistakes
This problem tests the coupling of the Superposition Principle with non-linear, temperature-dependent material properties via Curie's Law.
The primary trap lies in misidentifying which component of the superposed magnetic field contributes to eddy current heating; students often erroneously use the total RMS field, ignoring that static (DC) fields do not induce Faraday EMFs.
A secondary trap is failing to correctly superpose the orthogonal DC and AC components when calculating the final total RMS field ().
By forcing an iterative dependency analysis—where depends on , depends on , and depends strictly on the AC component of —the question rigorously evaluates the student's ability to isolate physical phenomena within superposed states.
Quick Facts About This Question
Question Information
| Subject | Physics |
| Chapter | Magnetism and Matter - Class 12 |
| Concept | Superposition of Magnetic Fields |
| Difficulty | 5 |
| Cognitive Load | 6 |
| Target Solve Time | 140 sec |
| Access | Free |