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Question #43253
The Question
A parallel plate capacitor with circular plates of radius is filled with a lossy dielectric material. The material has a relative permittivity (dielectric constant) and a uniform electrical conductivity . An alternating electric field is established inside the dielectric, where and . Neglecting edge effects, what is the amplitude of the induced magnetic field at a radial distance from the central axis of the capacitor? (Take and )
Options
- A.
- B.
- C.
- D.
Check Your Answer
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
Ampere’s Law Displacement Current|Maxwell's Correction to Ampere's Law|Vector Calculus
Why This Question Is Tricky
Common Mistakes
This question tests the student's understanding of the Ampere-Maxwell law in a non-ideal (lossy) dielectric medium.
A common misconception is that displacement current only exists in a vacuum or that conduction current is zero in any dielectric.
Students often calculate only the displacement current (Option B) or only the conduction current (Option C).
Furthermore, even if they recognize both exist, they may incorrectly add their amplitudes algebraically (Option D) instead of recognizing the 90-degree phase difference between the conduction current (in phase with the electric field) and the displacement current (proportional to the time derivative of the electric field).
The correct approach requires phasor addition of the current densities.
Quick Facts About This Question
Question Information
| Subject | Physics |
| Chapter | Moving Charges and Magnetism - Class 12 |
| Concept | Ampere’s Law Displacement Current |
| Difficulty | 8 |
| Cognitive Load | 7 |
| Target Solve Time | 160 sec |
| Access | Free |