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Question #43294
The Question
A rigid wire frame consists of two identical square loops, Loop 1 (left) and Loop 2 (right), each of side length , sharing a common vertical branch. The common branch contains an ideal parallel-plate capacitor of capacitance . The left vertical branch of Loop 1 has a resistance , and the right vertical branch of Loop 2 has a resistance . All other wire segments have negligible resistance. The frame lies in the plane. A spatially uniform magnetic field is confined to the region of Loop 1, and is confined to the region of Loop 2, where is a constant and is time. At , the capacitor is uncharged. Assuming the self-inductance of the loops is negligible, what is the magnitude of the displacement current through the capacitor as a function of time ?
Options
- A.
- B.
- C.
- D.
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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
Magnetic Flux Scalar Sign|Kirchhoff’s Loop Rule|Maxwell's Correction to Ampere's Law|Integration
Why This Question Is Tricky
Common Mistakes
This question tests the student's ability to rigorously apply Faraday's Law and Kirchhoff's Laws in a multi-mesh circuit with time-varying magnetic fields.
The primary trap lies in the sign convention of the induced EMFs when transitioning from loop equations to nodal analysis.
Because both magnetic fields point in the same direction (), students often incorrectly assume the induced EMFs will simply add or subtract algebraically without tracing the actual mesh current directions.
A clockwise current in the right loop corresponds to an EMF pointing downwards in the right branch, which acts with opposite polarity to the left loop's EMF relative to the top node.
Failing to account for this spatial boundary condition leads to an incorrect effective driving voltage (e.g., instead of ) and an incorrect displacement current.
Quick Facts About This Question
Question Information
| Subject | Physics |
| Chapter | Electromagnetic Induction - Class 12 |
| Concept | Magnetic Flux Scalar Sign |
| Difficulty | 8 |
| Cognitive Load | 7 |
| Target Solve Time | 160 sec |
| Access | Free |