Rebuild Progress & PYQ Retagging Changelog

ECE 2105 — Note Rebuild Progress & PYQ Retagging Changelog

What happened

Chapters 1–3 were rebuilt from the degraded atomic notes, merging content from the older monolithic master notes in electrostatics/, with every PYQ tag re-verified against [[ece 2105 field pyq]] and [[field checklist]].

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1. Status Board

File	Status
Chapter 1
01 Chapter Map - Vector Calculus & Fundamentals	✅ Rebuilt
1.01 Spatial Coordinates & Differential Elements (Cartesian, Cylindrical, Spherical)	✅ Rebuilt
1.02 Vector Operators (Gradient, Divergence, Curl & Laplacian)	✅ Rebuilt
1.03 Integral Theorems (Divergence Theorem & Stokes_s Theorem) & Identity Proofs	✅ Rebuilt
1.04 Media Properties & Conductor-Insulator Behaviour	✅ NEW
00 Chapter 1 Active-Recall Diagnostic Quiz	✅ Rebuilt (15 Q, collapsible answers)
Chapter 2
02 Chapter Map - Electrostatics & Boundary Conditions	✅ Rebuilt
2.01 Fundamental Postulates of Electrostatics & Gauss_s Law Applications	✅ Rebuilt
2.02 Electric Potential, Equipotential Contours & Dipole Derivations	✅ Rebuilt
2.03 Conductors, Dielectrics & Polarization Charge Densities	✅ Rebuilt
2.04 Electrostatic Boundary Conditions, Refraction Law & Poisson-Laplace Equations	✅ Rebuilt
2.05 Electrostatic Energy, Work Done & Solved PYQ Numericals	✅ NEW
00 Chapter 2 Active-Recall Diagnostic Quiz	⬜ TODO — still original
Chapter 3
03 Chapter Map - Magnetostatics & Magnetic Materials	⬜ TODO — still original
3.01 Fundamental Postulates of Magnetostatics & Lorentz Force Equation	⬜ TODO
3.02 Biot-Savart Law Applications (Finite Wire, Circular Loop, Coaxial Cable)	⬜ TODO
3.03 Ampere_s Circuital Law & Vector Magnetic Potential (A)	⬜ TODO
3.04 Magnetization, Magnetic Materials, Boundary Conditions & Hall Effect	⬜ TODO
3.05 Magnetic Dipole & Uniformly Magnetized Cylinder	⬜ TODO — to be created
3.06 Magnetic Forces, Torque & Energy	⬜ TODO — to be created
00 Chapter 3 Active-Recall Diagnostic Quiz	⬜ TODO

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2. What Was Wrong Before (and is now fixed)

Defect	Where it appeared	Fix
LaTeX stripped to plain text (grad . vec{A}, 4pi epsilon_0, hat{a}_r)	Ch 1 quiz, 2.02, 2.03, 3.01, 3.02, 3.03	All maths rewritten as proper $...$ / $$...$$
Escaped underscores inside math (\vec{M} \times \hat{a}\_n) — renders as a literal underscore, not a subscript	3.04	To be fixed in Ch 3 pass
Broken YAML frontmatter — status: enhanced--- merged onto one line	2.01	Valid frontmatter
Frontmatter leaked into the body as italic text	2.02, 3.02	Moved into real YAML
No frontmatter at all	1.01, 1.03, 2.03, 2.04, 3.01, 3.03, both chapter maps, Ch1/Ch2 quizzes	Full frontmatter added
Google Docs URLs instead of wikilinks	1.01	Real [[wikilinks]]
HTML entities in wikilinks (Ampere's) — link would never resolve	Ch 3 map	To be fixed in Ch 3 pass
Empty section — “Comparison: $\vec{E}$ vs $\vec{D}$” had a heading and no content	2.02	Full 7-row comparison table
Lost superscripts — R sin dR d d instead of $R^2\sin \theta dRd\theta d\varphi$	1.01	Restored
Greek letters deleted — (r, , z), 0 R <	1.01	Restored
Broken ASCII diagrams	1.01, 3.02, 3.04	Replaced with Mermaid diagrams + [FIGURE:] placeholders citing Cheng figure numbers

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3. PYQ Tag Corrections (bank = ground truth)

3.1 Tags REMOVED (no matching question exists in 2015–2025)

Note	Old tag	Why removed
1.03 §1 Divergence Theorem	[PYQ: 2015, 2016, 2020, 2022]	The Divergence Theorem has never been asked standalone. It is a syllabus/L2 tool used inside the postulate derivations. Replaced with an explicit scope note.
1.03 §2 Stokes’s Theorem	[PYQ: 2015, 2017, 2020, 2022]	Same — never asked standalone.
1.03 §3 Vector identity proofs	[PYQ: 2016, 2018, 2021]	Null identities have never been asked as their own question. Their consequences ($V$ and $\vec{A}$ exist) are examined instead.
1.03 §3.1 Curl of gradient	[PYQ: 2016, 2021]	Not in the bank.
1.03 §3.2 Divergence of curl	[PYQ: 2018]	Not in the bank.
1.03 §4 Circuit theory	2020 (within [PYQ: 2018, 2019, 2020, 2021])	2020 asked about quasi-static conditions, a different question. Now tagged separately under its own heading.
2.04 §3 Poisson & Laplace	2020, 2024	Neither year asked for the Poisson/Laplace derivation. Correct years are 2015, 2016, 2017, 2022, 2023, 2025.
3.01 §1 Magnetostatic postulates	[PYQ: 2015, 2016, 2018, 2021]	To be verified in Ch 3 pass — the magnetostatic postulates are not asked as a standalone “write both postulates” question the way the electrostatic ones are.

3.2 Tags CORRECTED

Note	Concept	Old	Corrected
2.04	Poisson’s equation derivation	2017, 2020, 2024	2015, 2016, 2017, 2022, 2023, 2025
2.02	Electric potential / $\vec{E}=-\nabla V$	2016, 2017, 2021, 2024, 2025	2016, 2017, 2021 (2024/2025 are the equipotential sketch question, now tagged separately)
2.01	Gauss’s law applications	untagged / partial	2015, 2016, 2019, 2020, 2023
2.01	Charged cloud derivation	”Heavily Tested: 2018, 2019, 2020, 2022”	2018, 2019, 2020, 2022 (kept — verified correct)
2.03	Conductor properties	2016, 2020	2016, 2020 (verified — this is the conductor/free-space boundary question)
1.02	Divergence significance	untagged	2018
1.02	Curl properties	untagged	2022

3.3 Tags ADDED (PYQ existed but had no coverage anywhere)

Concept	Years	Now in
Define homogeneous, linear, isotropic media	2015, 2017, 2019, 2023, 2024	1.04 Media Properties & Conductor-Insulator Behaviour
Good conductor vs good insulator conditions	2020	1.04 Media Properties & Conductor-Insulator Behaviour
Loss tangent / complex permittivity short notes	2019, 2022, 2023	1.04 Media Properties & Conductor-Insulator Behaviour
Meaning of ‘field’ + significance for an ECE engineer	2024	1.03 Integral Theorems (Divergence Theorem & Stokes_s Theorem) & Identity Proofs
Quasi-static conditions	2020	1.03 Integral Theorems (Divergence Theorem & Stokes_s Theorem) & Identity Proofs
Define metric coefficient	2019	1.01 Spatial Coordinates & Differential Elements (Cartesian, Cylindrical, Spherical)
$\vec{A},\vec{B},\vec{H},\vec{J}$ numerical at $P(3,-1,2)$	2022, 2025	1.02 Vector Operators (Gradient, Divergence, Curl & Laplacian)
Coulomb’s law + continuous distributions	2018, 2021	2.01 Fundamental Postulates of Electrostatics & Gauss_s Law Applications
Gauss’s law → infinite line charge potential	2016	2.01 Fundamental Postulates of Electrostatics & Gauss_s Law Applications
Work done = potential difference proof	2017	2.02 Electric Potential, Equipotential Contours & Dipole Derivations
$\vec{E}$ vs $\vec{D}$ (4-part distinction)	2022, 2025	2.02 Electric Potential, Equipotential Contours & Dipole Derivations
Equipotential line definition + 2D sketches	2024, 2025	2.02 Electric Potential, Equipotential Contours & Dipole Derivations
How dipole $V$ varies with distance and angle	2019	2.02 Electric Potential, Equipotential Contours & Dipole Derivations
Parallel-plate capacitance	2016, 2018, 2019, 2021, 2022, 2023, 2024, 2025	2.04 Electrostatic Boundary Conditions, Refraction Law & Poisson-Laplace Equations
Cylindrical capacitor	2015, 2017	2.04 Electrostatic Boundary Conditions, Refraction Law & Poisson-Laplace Equations
Electrohydrodynamic pump (Poisson with ${\rho }_v\ne 0$)	2024	2.04 Electrostatic Boundary Conditions, Refraction Law & Poisson-Laplace Equations
Solution of Poisson’s equation	2017, 2023	2.04 Electrostatic Boundary Conditions, Refraction Law & Poisson-Laplace Equations
”What if one medium is a conductor?“	2015	2.04 Electrostatic Boundary Conditions, Refraction Law & Poisson-Laplace Equations
Electrostatic energy — assemble $n$ charges	2018, 2022, 2023, 2024, 2025	2.05 Electrostatic Energy, Work Done & Solved PYQ Numericals
Energy stored in 4 point charges (numerical)	2019, 2020, 2023	2.05 Electrostatic Energy, Work Done & Solved PYQ Numericals
Work done carrying $-2\mu$C (numerical)	2022, 2025	2.05 Electrostatic Energy, Work Done & Solved PYQ Numericals
Rectangle centre potential (numerical)	2020	2.05 Electrostatic Energy, Work Done & Solved PYQ Numericals
$\vec{E}$, $V$ vs $R$ for a conducting shell	2025	2.05 Electrostatic Energy, Work Done & Solved PYQ Numericals
Point-charge numericals ($x=4$; $z=8$)	2016, 2017, 2018	2.05 Electrostatic Energy, Work Done & Solved PYQ Numericals

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4. Physics/Arithmetic Errors Found and Corrected

Where	Error	Correction
Old master notes, 2016/2018 numerical	Net field reported as $-1044.5$ V/m; the $x$-component of the $1\mu$C charges was divided by $\sqrt{20}$ twice	Correct $x$-component is $450\cos \theta =450(4/\sqrt{20})=402.5$ V/m, giving net $\approx -320$ V/m. Flagged explicitly in 2.05 Electrostatic Energy, Work Done & Solved PYQ Numericals §5.
3.04 Hall voltage	$V_H=BI/(nqw)$ with $w$ called the strip width	Dimensionally the denominator length must be the thickness along $\vec{B}$, not the width across which $V_H$ is measured: $V_H=BI/(nqt)$. To be fixed in the Ch 3 pass.
3.04 §2 diagram	ASCII figure mislabels $B_{1n}/B_{2n}$ and $H_{1t}/H_{2t}$ on the wrong sides of the interface	To be replaced in the Ch 3 pass

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5. To Resume — Chapter 3 Plan (already scoped, not yet executed)

Rebuild 3.01–3.04 in the same format, and create two new notes to close the biggest PYQ gaps in the vault:

Note	Content	PYQ years currently uncovered
3.01 (rebuild)	Two magnetostatic postulates, physical significance, Lorentz force, zero-work property	2018, 2021
3.02 (rebuild)	Biot-Savart statement, Biot-Savart vs Ampère comparison, finite wire $2L$, square loop, circular loop	2015, 2016, 2017, 2018, 2021, 2023, 2025
3.03 (rebuild)	Ampère’s law applications are currently missing entirely despite the note’s title — add $B$ inside/outside an infinite conductor; vector Poisson; $\vec{A}$ inside/outside a conductor; $\oint \vec{A}\cdot d\vec{l}=\Phi$; vector vs scalar magnetic potential	2015, 2016, 2017, 2018, 2019, 2020, 2021, 2022, 2024, 2025
3.04 (rebuild)	Magnetization, bound currents, material classification, boundary conditions, refraction law, Hall effect (fix the $V_H$ thickness error), boundary numericals (air–iron, ${\mu }_1=1$/${\mu }_2=2.4$)	2015–2025
3.05 (new)	Magnetic dipole, dipole moment, $B$ of a small circular loop at a distant point in terms of $\vec{m}$ — asked in 8 separate years (2015, 2016, 2017, 2018, 2019, 2021, 2022, 2025), electric vs magnetic dipole differences, uniformly magnetized cylinder / bar magnet, magnetic susceptibility	2015–2025 — currently no coverage at all
3.06 (new)	Force between parallel wires + Newton’s third law, torque on a rectangular loop, magnetic energy of $N$ loops, coupled circuits, electrostatic–magnetostatic analogy, energy stored in a magnetic field	2015, 2017, 2018, 2019, 2020, 2021, 2022, 2023, 2024, 2025 — currently no coverage at all
Ch 3 map + quiz	Rebuild; fix the Ampere's HTML-entity wikilink that currently cannot resolve	—

Also outstanding: 00 Chapter 2 Active-Recall Diagnostic Quiz still needs its LaTeX and collapsible-answer rebuild.

To resume

Say “continue the Chapter 3 rebuild” — the plan above is complete and the source material (electrostatics/03 magnetostatics_master_notes.md) has already been read and mapped.

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6. Conventions Used Throughout

• Frontmatter: title, aliases, tags (incl. study-order/x.yy), type, course, course_link, chapter_map, term, teacher, status
• Wikilinks use the real on-disk filenames — note Stokes_s, Gauss_s, Ampere_s use an underscore, not an apostrophe
• Callouts: [!abstract] definitions · [!example] derivations · [!question] PYQs · [!warning] traps · [!tip] shortcuts · [!info] background · [!important] high-frequency alerts
• Inline glosses: *{plain-language explanation}* for light jargon; > [!note] Terminology & Concept Breakdown when 3+ terms appear together
• PYQ tags: [PYQ: year, year] inline on headings, plus a full “PYQ Coverage” table with verbatim questions and marks at the end of each note
• Figures: never generated — [FIGURE: description — source: Cheng Ch. X, Fig. Y] and [GRAPH: equation + description] placeholders
• Every note ends with Exam Hacks & Traps, then Self-Check