Non-radiative mid-range wireless power transfer: An experiment for senior physics undergraduates
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Bibliographic record
Abstract
A wireless power transfer experiment suitable for senior physics undergraduates is described and demonstrated in detail. The apparatus, which operates between 3 and 4 MHz, consists of a pair of identical resonant coils that can be moved relative to one another. A signal generator circuit is inductively coupled to the transmitting coil using a single loop of wire. Likewise, a single loop of wire couples the receiving coil to a load impedance. We use a matching circuit to tune the impedance of the system of coupled resonators to match the 50-Ω output impedance of the signal generator and a low-cost vector network analyzer to characterize the system performance as the distance between the pair of coils is changed. We find that when the distance between the transmitting and receiving coils is small, a double resonance emerges and that the frequency difference between the pair resonances is inversely proportional to the distance between the coils. After fully characterizing the system, it can be operated up to an incident power of 20 W. Our measurements reveal that, at weak coupling, the fraction of the incident power lost to radiation increases linearly with the distance between the coils. Finally, we demonstrate that the system is able to transmit enough power to dimly light a 60-W incandescent light bulb.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it