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Question #43865
The Question
A small dielectric cylinder of length and cross-sectional area is placed along the -axis from to . It is subjected to a uniform external electric field . The material's electric susceptibility follows a Curie-like temperature dependence, , where is a constant and (so the internal field is approximately ). A temperature gradient is maintained across the cylinder such that , where . Let be the dipole moment of the cylinder if it were at a uniform temperature . Find the electric potential at a point on the axis (). Retain the leading order term and the first non-vanishing correction term involving .
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
Electric Field Symmetry|Dipole Potential Angular Dependence|Curie’s Law|Binomial Approximation
Why This Question Is Tricky
Common Mistakes
This question tests the fundamental understanding of bound charges in dielectrics and multipole expansions.
Students often correctly identify the temperature dependence of polarization (Curie's Law) but fall into the trap of only calculating the modified surface bound charges .
Because the polarization is non-uniform due to the temperature gradient, a volume bound charge is generated.
Ignoring this volume charge leads to an incorrect quadrupole moment (Option B).
Furthermore, it tests the ability to recognize that a spatial gradient in susceptibility breaks the pure dipole symmetry, requiring a binomial expansion to find the far-field potential correction.
Quick Facts About This Question
Question Information
| Subject | Physics |
| Chapter | Electric Charges and Fields - Class 12 |
| Concept | Electric Field Symmetry |
| Difficulty | 8 |
| Cognitive Load | 7 |
| Target Solve Time | 160 sec |
| Access | Free |