ECE 230, Winter 2020

Fields and waves

Instructor
Sayak Bhattacharya
Office hour: Mon, 5-6pm (B603, R&D Block) E-mail: sayak|at|iiitd.ac.in

Lectures: Mon, Fri 2:30-4:00pm (Room: A007)
Tutorials: Wed 2:30-3:30pm ((Room: A106,B105,A006))

Teaching Assistants
Yashwant Jain
Shalin Verma
Dinesh Rano
Office hours: By appointment

Announcements

  • Click here to download assignment 2. Deadline is 6 p.m., April 3. Email your answer scripts to the instructor.

  • Click here to download assignment 1. New deadline is 6 p.m., March 21. Email your answer scripts to the instructor.

  • Mid-semester examination (syllabus: till lect. 10) to take place on Feb. 20, 2020 (Thurs), 10-11:30am @C21

  • Electromagnetic poster day temporarily cancelled due to COVID-19. A new date 'll be announced in due time. But keep studying your topics. [Guidelines: Form a group of 4 and select a topic related to Electromagnetics in nature or Electromagnetics in industry. The topics 'll be reviewed for technical richness before you start preparing for the poster day. All 4 members of the group needs to present and answer questions. Other faculty members 'll evaluate your performances and grade you].

  • Fri, Jan 31, 2020: No lecture (research showcase day).

  • Wed, Jan 08, 2020: tutorial to be held only in A106 (for all groups).

  • Course webpage online! The first lecture 'll be on Fri, Jan. 3, 2020.

Lectures

S. No. Date Topic Advised Reading Lectures
1 Jan 3 Course outline & grading policy, Introduction & historical background
Review of vector calculus
Griff. ch 1, Sad. ch 1, 2, 3
Feyn. ch 1,2
Slides
2 Jan 6 Different coordinate systems, Line integral & conservative fields
Volume, surface integral & divergence theorem
Earnshaw's theorem & Paul trap
Griff. ch 1, Sad. ch 2, 3
Feyn. ch 2
Slides
3 Jan 10 Stoke's theorem, Dirac delta function in 3D & volume charge density of point charges
How much is divergence of a radially directed inverse square function
Coulomb's law and Gauss's law
Griff. ch 1, ch 2
Slides
Lecture note
4 Jan 13 Electrostatic potential, potential due to charge distribution, Equipotential surface, Demo starts at 44:00
Perfect conductors, Electric field and volume charge inside a perfect conductor, perfect conductors as equipotentials
Electrostatic boundary conditions Poisson's and Laplace's eq., solving Laplace's eq.
Griff. ch 2, for solution of Laplace's eq. Griff. ch 3
Lecture note
5 Jan 20 Energy of an assembly of point-charges, Electrostatic energy density, Electrostatic field inside a material
Induced dipole and dipole moment of polar molecules
Polarization vector, bound charges, Gauss's law in presence of a material medium Physical interpretation of bound surface and volume charge densities: are they real?
For the first two topics: Griff. ch 2; Griff. ch 4 for the rest
Lecture note
6 Jan 21 Surprise quiz 1 of 5

Questions
Solutions
7 Jan 24 Lorentz force law, demo at 14:08 , Parallel and anti-parallel currents, demo at 15:38
Charged particles in non-uniform magnetic fields, Greatest Electromagnetic show on the earth: Aurora
Force on a current-carrying wire, surface and volume current density
More on currents: Ohm's law and eqn. of continuity
Relaxation time: conductors and insulators
Griff. ch 5
Lecture note
8 Jan 27 Biot-Savart Law,Divergence and curl of magnetic field, Ampere's law
Magnetic vector potential and its non-uniqueness
Griff. ch 5
Lecture note
9 Feb 03 Quiz 2 of 5
Open-classnote

Questions
10 Feb 07 Boundary conditions for tangential and normal components of magnetic field
Magnetic field in matter
Magnetic dipole in a uniform magnetic field
Force on a magnetic dipole in a non-uniform magnetic field: paramagnetismDemo starts at 41:00 (liquid hanging from a magnet!)
Magnetization, Ampere's law for magnetized materials, magnetic susceptibilty and permeability
para, dia and ferromagnetic materials
Demo starts at 21:55 (You can listen to the domains in a ferromagnetic material as they flip)
Demo starts at 35:51 (Curie temperature)
Griff. ch 5 for magnetic field boundary conditions, Griff. ch 6 for the rest
Lecture note
11 Feb 10 Review of quiz 2
A glitch in Ampere's law: Introduction to Electrodynamics
Griff. 7.3.1 and 7.3.2
12 Feb 14 EMF and Faraday's law of induction
Griff. ch 7
Lecture note
13 Feb 28 Quick recap: Faraday's law of induction and Maxwell's modification to Ampere's law
Maxwell's equations: differential form, integral form, time-domain and frequency domain
Concept of complex and frequency dependent permittivity
Griff. ch 7
Lecture note
14 Mar 2 EM wave propagation: a physical picture, Polarization of EM waves, Displacement current
High frequency behavior of circuits: introduction to transmission line
Working mechanism of a transmitting antenna: Demo 1, Demo 2
Working mechanism of a receiving antenna: Demo
Potentials in Electrodynamics, Gauge freedom, Coulomb gauge and Lorentz gauge
Griff. ch 10.1
Lecture note
15 Mar 6 Dispersive medium: origin and frequency dependence of dielectric constant
Scalar wave equation
Electromagnetic wave equation, Helmholtz equation
Griff. ch 9 (Electromagnetic Waves)
Lecture note
16 Electromagnetic wave equation in 1D: uniform plane wave
Electromagnetic wave equation in 3D
Griff. ch 9
(Electromagnetic Waves)
Lecture note,
Video
17 Poynting's theorem
Electromagnetic waves in materials: attenuation in conducting materials, skin depth
Poynting's theorem: Griff. ch 8, Griff. ch 9 for the rest
Lecture note


Practice problems

Set 1 (covers till lecture 8)



Tutorials

Tutorial 1
Tutorial 2
Tutorial 3 and 4
Tutorial 5
Tutorial 6
Tutorial 8


References

  • David J. Griffiths, Introduction to Electrodynamics, Pearson 4th Ed. (2015).

  • R. Feynman, R. Leighton, M. Sands, The Feynman Lectures on Physics (Vol II)

  • Matthew. N. O. Sadiku, Elements of Electromagnetics.