Before You Begin
Question #43076
The Question
A long straight wire carries an alternating current , where is the current amplitude in Amperes and is the angular frequency in rad/s. A rigid rectangular conducting loop of side lengths and (in meters) is placed in the same plane as the wire. The side of length is parallel to the wire and is at a distance (in meters) from it. The loop has a constant self-inductance (in Henries). Due to high-frequency skin effects, the effective resistance of the loop is strictly proportional to the angular frequency, given by , where is a positive constant in Henries. Let be the mutual inductance (in Henries) between the wire and the loop. What is the total electrical energy dissipated as heat in the loop during exactly one complete cycle of the alternating current?
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
Transformer Flux Linkage|Dynamic Resistance (AC Resistance)|Magnetic Flux Scalar Sign
Why This Question Is Tricky
Common Mistakes
This question tests the student's ability to integrate Faraday's Law with frequency-dependent AC circuit analysis, specifically targeting the misconception that higher driving frequencies always result in higher energy dissipation per cycle.
Students often blindly apply while ignoring the inductive reactance , leading to the incorrect assumption that inductance doesn't limit the current (Option B).
Alternatively, they might confuse active power with reactive power, using instead of the power factor (Option C).
The core trap lies in realizing that because both the dynamic resistance () and the inductive reactance () scale linearly with , the impedance scales with , making the induced current amplitude and the energy dissipated per cycle completely independent of the driving frequency.
Quick Facts About This Question
Question Information
| Subject | Physics |
| Chapter | Alternating Current - Class 12 |
| Concept | Transformer Flux Linkage |
| Difficulty | 8 |
| Cognitive Load | 7 |
| Target Solve Time | 160 sec |
| Access | Free |