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Question #43363

Difficulty: 8/10 | 🟢 Free

The Question

A solid conductor is shaped as a spherical sector (a truncated cone bounded by two spherical caps centered at the apex). The inner spherical cap has a radius r1=Rr_1 = R and the outer spherical cap has a radius r2=3Rr_2 = 3R. The solid angle subtended by the sector at the apex is Ω\Omega. The conductor is made of a non-Ohmic material where the local electric field magnitude EE and current density magnitude JJ are related by E=βJ2E = \beta J^2, where β\beta is a positive constant. A steady current II flows radially outward from the inner cap to the outer cap. The conductor is conceptually divided into two segments by an intermediate spherical cap of radius r=2Rr = 2R. What is the ratio of the total power dissipated in the inner segment (R≤r≤2RR \le r \le 2R) to that in the outer segment (2R≤r≤3R2R \le r \le 3R)?

Options

  • A.

    18919\frac{189}{19}

  • B.

    3

  • C.

    719\frac{7}{19}

  • D.

    2710\frac{27}{10}

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Correct Answer

Step-by-Step Solution

Explanation

How the Examiner Thinks

Intuition_Breaker

Train your brain to resist "obvious" answers that are designed to deceive your intuition.

Concepts Behind This Question

Power Dissipation Ratio|Potential Gradient Direction|Vector Cross-Product

Why This Question Is Tricky

Common Mistakes

This question tests the fundamental field-theoretic definition of power dissipation P=∫E⃗⋅J⃗dVP = \int \vec{E} \cdot \vec{J} dV in a non-uniform, non-Ohmic geometry.

The 'Lethal Collision' occurs when students blindly apply Ohmic formulas (yielding a ratio of 3) or assume a constant current density JJ (yielding a ratio of 7/19 based purely on volume).

By forcing the current density lines to diverge radially in a non-Ohmic medium (E=βJ2E = \beta J^2), the local power density dP/dVdP/dV becomes proportional to 1/r61/r^6, requiring students to abandon 1D circuit approximations and correctly integrate the spatially varying fields.

Quick Facts About This Question

Question Information

SubjectPhysics
ChapterCurrent Electricity - Class 12
ConceptPower Dissipation Ratio
Difficulty8
Cognitive Load7
Target Solve Time160 sec
AccessFree