Magnetic Architecture

NODE 01

Mag Phenomenon

N

S

• Magnets attract/repel. Compasses align.
• Current affects compasses.
• Where does magnetism come from?

NODE 02

Magnets

N

S

N

S

• Permanent magnets, N/S poles.
• Isolated magnetic poles NOT observed.

NODE 03

Magnetic Field

• Vector field describing magnetic influence.
• Symbol B. SI Unit: Tesla (T).
• Magnetic field ≠ magnetic force.

NODE 04

Field Lines

N

S

• Density = strength. Tangent = direction.
• Form CLOSED continuous loops.
• (Unlike E-fields which begin/end on charges).

NODE 05

Earth's Mag Field

• Large-scale magnetic system.
• Geographic vs magnetic poles.
• Declination, inclination/dip.

NODE 06

Moving Charge

• A moving electric charge produces magnetic effects.
• Electric charge + motion → magnetic effect.

NODE 07

Current as Source

• Connects to Realm 16.
• Current-carrying conductor produces B-field.
• Core experimental discovery.

NODE 08

Oersted's Exp

• Current-carrying wire → compass deflection.
• Meaning: Electric current produces B-field.

NODE 09

Right-Hand Rule

• Thumb → conventional current.
• Curled fingers → magnetic-field direction.

NODE 10

Straight Wire

• B = μ₀I/(2πr).
• Inverse dependence on distance.
• Circular field lines around wire.

NODE 11

Superposition

• Fields add vectorially: B_tot = B₁ + B₂ + ...
• Uses Realm 03 vector math.

NODE 12

Parallel Wires

• F/L = μ₀I₁I₂/(2πd).
• Same direction → Attract. Opposite → Repel.
• Current → B-Field → Magnetic Force.

NODE 13

Ampère's Law

• Central symmetry law: ∮ B·dl = μ₀I_enc.
• Closed Amperian loop, enclosed current.

NODE 14

Using Ampère

• Best suited for highly symmetric situations.
• Straight conductor, ideal solenoid, toroid.
• Symmetry → choose loop → solve B.

NODE 15

Biot-Savart Law

• dB = (μ₀/4π) I (dl × r̂)/r².
• Local contribution of a current element.
• Cross product.

NODE 16

B-S vs Ampère

B-S:GENERAL

AMP:SYMMETRY

• B-S: General field-building method.
• Ampère: Powerful when symmetry is simple.
• Complementary tools.

NODE 17

Circular Loop

• Strongest near centre.
• At centre: B = μ₀I/(2R).
• Direction via right-hand rule.

NODE 18

Loop Axis

• B = μ₀IR² / [2(R² + x²)^(3/2)].
• Advanced extension of circular loop.

NODE 19

Solenoids

• Long coil, many turns. B ≈ μ₀nI.
• Strong internal field, weak external field.
• n = turns per unit length.

NODE 20

Electromagnets

• Current + coil + magnetic material.
• Controllable magnetism (Relays, motors).

NODE 21

Toroid

• Confines field within core region.
• B = μ₀NI/(2πr).
• Circular magnetic path.

NODE 22

Dipole Moment

• For a current loop: μ = IA n̂.
• Gives loop a magnetic identity. Vector nature.

NODE 23

Torque on Loop

• τ = μB sinθ (τ = μ × B).
• Magnetic field creates rotation via torque.
• Connects to Realm 05.

NODE 24

PE of Dipole

• U = -μ·B = -μB cosθ.
• Stable when dipole aligns with field.

NODE 25

Galvanometer

• Electrical current → magnetic torque → rotation.
• Deflection against restoring torque.

NODE 26

Mag Force (Prev)

• Current in B-field experiences force.
• Sets the gate to Realm 18 (Lorentz force).

NODE 27

Materials

• Diamagnetic, Paramagnetic, Ferromagnetic.

NODE 28

Diamagnetism

• Weak induced response opposing applied field.
• Negative magnetic susceptibility.

NODE 29

Paramagnetism

• Weakly align magnetic moments with field.
• Unpaired electrons. Temperature dependent.

NODE 30

Ferromagnetism

• Strong collective magnetic ordering.
• Domains, strong magnetization, hysteresis.
• Iron, Cobalt, Nickel.

NODE 31

Magnetic Domains

• Regions with aligned magnetic moments.
• Domain walls. Alignment creates magnetization.

NODE 32

Hysteresis

• B/H magnetization curves.
• Saturation, retentivity, coercivity, loss.

NODE 33

Soft vs Hard Mat

• Soft: Easy to magnetize/demagnetize.
• Hard: Retains magnetization (permanent magnets).

NODE 34

Magnetic Flux

• Φ_B = ∫ B·dA.
• Φ_B = BA cosθ.
• Bridge to EM induction.

NODE 35

Gauss's Law (Mag)

• No isolated monopole sources.
• ∮ B·dA = 0. Field lines form closed loops.

NODE 36

Field Energy

u = B²/(2μ₀)

• Magnetic fields store energy.
• Prepares for inductors in Realm 19/20.

NODE 37

Mag Shielding

• Flux redistribution using magnetic materials.
• Freq and material dependent (not just "blocking").

NODE 38

Mag Technology

⚙️📻💽

• Motors, generators, speakers, relays.
• Transformers, MRI, data storage.

NODE 39

Mag in Nature

• Solar magnetic fields, sunspots, aurorae.
• Planetary magnetospheres.

NODE 40

Field Map Lab

• Compass mapping around bar magnet.
• Observe deflection near wires/loops/solenoids.

NODE 41

Ampere / B-S Lab

B ∝ IB ∝ 1/rB ∝ nI

• Connect mathematical laws to measurement.

NODE 42

Mag Force Exp

• F ∝ I, F ∝ L, F ∝ B.
• Sets up Realm 18.

NODE 43

Visualization

• Interactive diagrams for wires, loops, solenoids.

NODE 44

Misconceptions

X

• "Field lines are physical tubes" → No.
• "Poles can be isolated" → Not classically.
• "B-field does work on free charge" → No, F is perp to v.

NODE 45

Solving Engine

• ID Current Dist → Draw Field → RHR.
• Symmetry? Ampère. Otherwise: Biot-Savart.
• Superposition, Dipoles, Materials.

NODE 46

Master Map

MOVING CHRGMAGNETIC FIELDBIOT-SAVART / AMPERE

• Current → Field Lines → RHR → Laws.
• Loop → Solenoid → Toroid → Dipole → Torque.
• Materials → Domains → Hysteresis → Flux.

NODE 47

Deep Synthesis

CHARGE→ E-FIELD→ B-FIELD

• R15: Charge → E-field.
• R16: Moving charge → Current.
• R17: Current → B-field.
• Electricity & Magnetism are one system.