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Electromagnetics

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• Instructor: 안병철 교수(bician@cbu.ac.kr)

E10동611호(043-261-3194)

• Graders: 연걸, 장경월 (E10동519호, 043-261-3194)

• Text: Fundamentals of Applied Electromagnetics – F. T. Ulaby (6th Edition)

• Class: W10-11:50 am, F11-11:50am

(E8-7동426호)

• Self-study sessions: Friday class hour

• HWs due: Beginning of class

Logistics

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1st midterm 6th Week 20% 2nd midterm 12th Week 20% Final 15th Week 20% Class attendance 3 lates = 1 abs 10% Homeworks Every 3 weeks 15% Self study Friday class 15%

Grading Info (Dates tentative)

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Syllabus

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Text/References 교재: 전자기학, 7판, 김강욱, 김남, ...(Ulaby원저)

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On the Web

Hyperphysics at Georgia Tech (http://hyperphysics.phy-astr.gsu.edu)

http://www.magnet.fsu.edu/education/tutorials/webresources.html

Caltech Physics Applets (http://hyperphysics.phy-astr.gsu.edu)

http://www.falstad.com/mathphysics.html Physics 2000 (UC Boulder) http://www.colorado.edu/physics/2000/index.pl

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Hyperphysics at Georgia Tech (http://hyperphysics.phy-astr.gsu.edu)

Caltech Physics Applets (http://hyperphysics.phy-astr.gsu.edu)

Do not forget

Wikipedia (http://www.wikipedia.org)

How Stuff Works (http://www.howstuffworks.com)

8 Jeff Buchino http://www.cartoonclipart.com

http://cartoonworks.gospelcom.net/clipart.html

Honor Policy

… as far as possible …

Classroom Etiquette

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Ch1-Overview

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Calculus

Trig

Geometry

Area? Perimeter?

Area? Volume?

Area? Volume?

sin2θ, sin(A+B), cosA + cosB, sin2θ + cos2θ

Integration by change of variables Derivatives, Chain Rule Simple PDEs

Maths

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1.Read day-to-day summaries for qualitative overview 2. Listen to lecture slide recordings 3. List important equations to remember 4. List important math formulae (calculus, trig) 5. Go over Mock Exam and solutions 6. Go over HWs and solutions

DO NOT LEAVE FOR THE LAST MOMENT!!

Make sure you can do these (& similar!) problems ON YOUR OWN !!

Six things to do before exams

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formula (포'뮬러) formulas, formulae (포'뮬리)

stimulus stimuli (스티'뮬라이)

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1.Be regular 2. Try to understand, not memorize 3. Challenge yourself with the concepts 4. Brush up on maths (this is often the killer!) 5. Avoid careless mistakes at exam (CHECK!) 6. Revise

Six keys to success

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Why Electromagnetism?

Polaroids Rainbows

Lightning

Laser

Northern Lights

Telescope

15 Electronic Gadgets

Why Electromagnetism?

16 Chemistry and Biology

Chemical Reactions

Biological Processes

Neural Impulses

Ion Channels

Why Electromagnetism?

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Topics to Discuss

• History of Electromagnetics • Overview of the class • New trends

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Transmission Line LOAD

• Transmission line equations • Characteristic impedance of a line • How much is reflected at a load? • How would one eliminate this reflection? • What about transient pulses?

How do EM Fields Propagate?

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How do static charges interact? (Electrostatics)

Coulomb’s Law Force ∝ q1q2/r2

Gauss’s Law Flux ∝ q1 + q2 + ..

Interaction in materials (Polarization)

q1 q2

F2 F1 r

+

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Vector Fields (A “disturbance in the force”)

E = lim F/q q 0

q

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Vector Fields (A disturbance in the force)

Non-negligible q

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I

H r

Biot-Savart’s Law Current magnetic field

H ~ I/r

dl1

I1

I2

dl2

R i12

i21

Force ~ i2 x H

Another current senses it

How do magnetic fields interact? (Magnetostatics)

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Time variation couples E and H

I

H r

Faraday’s Law Varying H produces E

Ampere’s Law Varying E produces H

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Electrodynamics

Maxwell’s Eqns. Coulomb/Gauss’ Law

Gauss’ law for magnets

Ampere’s Law

Faraday’s Law

Varying E produces H produces E produces H ..

E E E E H H H

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Electrodynamics

Coulomb/Gauss’ Law

Gauss’ law for magnets

Ampere’s Law

Faraday’s Law

Don’t worry about memorizing these yet – We will come back to these later. But meanwhile, let’s try to understand them qualitatively....

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Deciphering Maxwell’s equations

I

H r

Electric fields diverge but don’t curl

Magnetic fields curl but don’t diverge

Q

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Deciphering Maxwell’s equations

I

H r

Electric fields diverge but don’t curl (they start and end on charges or ‘poles’)

Magnetic fields curl but don’t diverge (they loop on themselves since there are no magnetic poles)

Q

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We thus have Maxwell’s equations in their simplest form (for static sources, in vacuum)

I

H r

Div(E) ∝ Q Curl(E) = 0

Q

Curl(H) ∝ I Div(H) = 0

We will define Div and Curl precisely later on. For now, think of them as the number of diverging and curling lines respectively

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We thus have Maxwell’s equations in their simplest form (for static sources, in vacuum)

Div(E) ∝ Q Curl(E) = 0

Curl(H) ∝ I Div(H) = 0

• Varying E produces H produces E produces H ..

• E • E • E • E • H • H • H

Note how E and H equations are independent of each other !! This is true for static sources For dynamic sources (time-dependent currents), you also get dH/dt terms for the E equations and dE/dt terms for the H equations, which couple them.

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Consequences of Maxwell’s equations

Waves Radiation

31 Interference Diffraction Polarization

Wave optics λ > d

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Geometrical Optics λ << d

Mirrors Lenses

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For the aspiring scientists/ engineers

What lies beyond Maxwell (1873)?

Will this be in your exams?

NO

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Nanoparticle optics Visible light = 380-620nm

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“Anomalous Optics” Negative refraction

Laws are reversed ! Applications: Reverse Doppler, perfect lens

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Quantum optics: Photonic Bandgap Materials

periodic structure (period = half wavelength): total reflection at resonance, total transmission off

ressonance

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Cellphone interactions with head

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Coherent optics – Lasers coherence = same frequency, constant phase difference; produces stationary interference

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Maxwell’s equations hold for all systems, from large objects to

nanoscale…

Solar Discharge (~1.4 x 109 m dia)

Molecular fields (~10-8 m dia)

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…. From ultrafast to ultraslow

Cerenkov Radiation (when a particle outruns its field) Optical equivalent of a sonic boom

Optical Molasses/Condensates Slow light down from 1.02 billion km/hr to 1.6 km/hr !! (Lene Hau, Harvard physicist)

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Even in Sci-Fi !