Chapter 13: Foucault Or Eddy Currents
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Source Metadata
Section titled “Source Metadata”| Field | Value |
|---|---|
| Source | Theory and Calculation of Alternating Current Phenomena |
| Year | 1916 |
| Section ID | theory-calculation-alternating-current-phenomena-chapter-13 |
| Location | lines 13484-14333 |
| Status | candidate |
| Word Count | 3721 |
| Equation Candidates In Section | 0 |
| Figure Candidates In Section | 3 |
| Quote Candidates In Section | 0 |
Opening Source Excerpt
Section titled “Opening Source Excerpt”CHAPTER XIII FOUCAULT OR EDDY CURRENTS 105. While magnetic hysteresis due to molecular friction is a magnetic phenomenon, eddy currents are rather an electrical phenomenon. When iron passes through a magnetic field, a loss of energy is caused by hysteresis, which loss, however, does not react magnetically upon the field. When cutting an electric conductor, the magnetic field produces a current therein. The m.m.f. of this current reacts upon and affects the magnetic field, more or less; consequently, an alternating magnetic field cannot penetrate deeply into a solid conductor, but a kind of screening effect is produced, which makes solid masses of iron unsuitable for alternating fields, and necessitates the use of laminated iron or iron wire as the carrier of magnetic flux. Eddy currents are true electric currents, though existing in minute circuits; andSource-Located Theme Snippets
Section titled “Source-Located Theme Snippets”Magnetism
Section titled “Magnetism”CHAPTER XIII FOUCAULT OR EDDY CURRENTS 105. While magnetic hysteresis due to molecular friction is a magnetic phenomenon, eddy currents are rather an electrical phenomenon. When iron passes through a magnetic field, a loss of energy is caused by hysteresis, which loss, however, does not react magnetically upon the field. When cuttin ...Field language
Section titled “Field language”CHAPTER XIII FOUCAULT OR EDDY CURRENTS 105. While magnetic hysteresis due to molecular friction is a magnetic phenomenon, eddy currents are rather an electrical phenomenon. When iron passes through a magnetic field, a loss of energy is caused by hysteresis, which loss, however, does not react magnetically upon the field. When cutting an electric conductor, the magnetic field produces a current therein. The m.m.f. of this current reacts upon and affects the magnetic field, more or less ...Radiation / light
Section titled “Radiation / light”... e of laminated iron or iron wire as the carrier of magnetic flux. Eddy currents are true electric currents, though existing in minute circuits; and they follow all the laws of electric circuits. Their e.m.f. is proportional to the intensity of magnetization, B, and to the frequency, /. Eddy currents are thus proportional to the magnetization, B, the frequency, /, and to the electric conductivity, X, of the iron; hence, can be expressed by i = bXBf. The power consumed by eddy currents is proportional to their square, and inversely proportional to t ...Impedance / reactance
Section titled “Impedance / reactance”... E = V2Tr AnfB 10-^, it follows that, The loss of power by eddy currents is proportional to the square of the e.m.f., and proportional to the electric con- ductivity of the iron; or, P = aE^\. 136 FOUCAULT OR EDDY CURRENTS 137 Hence, that component of the effective conductance which is due to eddy currents is P . that is, The equivalent conductance due to eddy currents in the iron is a constant of the magnetic circuit; it is independent of e.m.f., frequency, etc., but proportional to the electric conductivity of the iron, X. Eddy currents, l ...Chapter-Local Concept Hits
Section titled “Chapter-Local Concept Hits”| Concept Candidate | Hits In Section | Status |
|---|---|---|
| Frequency | 14 | seeded |
| Ether | 3 | seeded |
| Light | 2 | seeded |
| Magnetic permeability | 1 | seeded |
Chapter-Local Glossary Hits
Section titled “Chapter-Local Glossary Hits”| Term Candidate | Hits In Section | Status |
|---|---|---|
| ether | 3 | seeded |
| effective resistance | 1 | source-located candidate |
Equation Candidates
Section titled “Equation Candidates”| Candidate ID | OCR / PDF-Text Candidate | Source Location |
|---|---|---|
| No chapter-local candidates yet | - | - |
Figure Candidates
Section titled “Figure Candidates”| Candidate ID | OCR / PDF-Text Candidate | Source Location |
|---|---|---|
theory-calculation-alternating-current-phenomena-fig-092 | magnetic flux inclosed by the zone is SuV. Fig. 92. Hence, the e.m.f. generated in this zone is | line 13742 |
theory-calculation-alternating-current-phenomena-fig-093 | 93. Fig. 93. 110. Demagnetizing, or screening effect of eddy currents. | line 13860 |
theory-calculation-alternating-current-phenomena-fig-094 | du Fig. 94. The current inclosed by this zone is /„ | line 14074 |
Hidden-Gem Quote Candidates
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| No chapter-local candidates yet | - | - |
Modern Engineering Reading Prompts
Section titled “Modern Engineering Reading Prompts”- Magnetism: Track flux, reluctance, permeability, magnetizing force, and loss language against modern magnetic-circuit terminology.
- Field language: Read for whether field language is mechanical, geometrical, causal, descriptive, or simply a convenient engineering model.
- Radiation / light: Compare the chapter’s radiation vocabulary with modern electromagnetic radiation, spectral frequency, wavelength, absorption, and illumination engineering.
- Impedance / reactance: Translate historical opposition terms into modern impedance, admittance, conductance, susceptance, and complex-plane notation.
- Alternating current: Compare Steinmetz’s AC language with modern sinusoidal steady-state analysis, RMS quantities, phase, and phasor notation.
Ether-Field Interpretive Boundary
Section titled “Ether-Field Interpretive Boundary”- Magnetism: Centrifugal/divergent magnetic-field readings are interpretive overlays, not automatic historical claims.
- Field language: Field-pressure or field-gradient interpretations can be explored here only after the explicit source passage and modern engineering translation are kept distinct.
- Radiation / light: Radiation and wave language can invite ether-field comparison, but source wording, modern radiation theory, and speculative synthesis must stay separated.
Promotion Checklist
Section titled “Promotion Checklist”- Open the full source text and the scan or raw PDF.
- Verify the chapter boundary and surrounding context.
- Promote exact quotations only after checking the source image.
- Move mathematical candidates into canonical equation pages only after formula typography is corrected.
- Move diagram candidates into the diagram archive only after image extraction, crop verification, and manifest creation.
- Keep Steinmetz wording, modern translation, and ether-field interpretation in separate labeled layers.