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Question #42024
The Question
A primary coil is driven by an alternating current . A secondary coil with self-inductance and negligible resistance is magnetically coupled to the primary with a mutual inductance . The secondary coil is connected in series with a load . The reference direction for the secondary current is chosen such that positive and positive produce magnetic flux in the same direction in the core. Let be the phase difference such that the steady-state secondary current is with . If is the phase difference when is an ideal inductor , and is the phase difference when is an ideal capacitor (where ), what are the values of and respectively?
Options
- A.
and
- B.
and
- C.
and
- D.
and
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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
The Directional Sign Convention|Lenz’s Law Energy Conservation|Transformer Flux Linkage
Why This Question Is Tricky
Common Mistakes
This question tests the rigorous application of Lenz's Law and directional sign conventions in coupled circuits.
Students commonly rely on rote memorization, assuming an inductor causes a phase lag and a capacitor causes a phase lead relative to the source.
However, by explicitly defining the reference direction for the secondary current such that the fluxes add, the induced EMF carries a strict negative sign ().
This forces the secondary current to be exactly out of phase () for an inductive load to oppose the primary flux change, and exactly in phase () for a dominant capacitive load due to the double time-derivative flipping the sign.
Failing to account for the coordinate-dependent flux linkage leads to standard phase-errors.
Quick Facts About This Question
Question Information
| Subject | Physics |
| Chapter | Motion in a Straight Line - Class 11 Part 1 |
| Concept | The Directional Sign Convention |
| Difficulty | 8 |
| Cognitive Load | 7 |
| Target Solve Time | 160 sec |
| Access | Free |