Lecture 1 Notes, 95.658, Spring 2012, Electromagnetic Theory II
Dr. Christopher S. Baird, UMass Lowell
1. Review Class Policy and Syllabus
2. Overview of Electrodynamic Theories
LOW SPEED
HIGH SPEED (close to speed of light)
BIG SIZES
Classical Electrodynamics
(includes electrostatics, magnetostatics)
Maxwell Equations
Relativistic Electrodynamics
Covariant Maxwell Equations
SMALL SIZES (atomic)
Classical Quantum Electrodynamics
Schrödinger Equation
Relativistic Quantum Electrodynamics
Dirac Equation
3. Overview of the Course
- Last semester we covered electrostatics, magnetostatics, pseudo-magnetostatics, and an
introduction to electrodynamics.
- This semester we will study electrodynamics in depth, as well as special relativity and relativistic
electrodynamics, which is best handled in covariant form.
- In electrodynamics, changing magnetic fields can give rise to electric fields which in turn can give
rise to new magnetic fields. This feedback process continues indefinitely and a self-sustaining
electromagnetic wave propagates and becomes independent of any electric charges or currents.
- Seen from a physical perspective, every
electrodynamic
system necessarily involves
electromagnetic waves, whether created, destroyed or transmitted.
- We will therefore focus this semester on:
- The interaction of waves with materials (reflection, refraction, dispersion, absorption)
- Bounded electromagnetic waves (waveguides, cavities)
- The creation of electromagnetic waves (radiation, antennas, etc.)
- The interaction of waves with objects (scattering)
- Special relativity
- In this course, a self-sustaining electrodynamic field will be referred to as a “wave” or as “light”.
Although in many contexts the word “light” narrowly refers to visible light, it is used in this course
to mean any electromagnetic wave of any frequency (radio waves, microwaves, X-rays, etc.) and
even those without well-defined frequencies.
- It should be noted that waves that are on the high-frequency end of the spectrum (gamma rays, X-
rays, ultraviolet, and often even visible) have such a small wavelength that they are often better
described using quantum electrodynamics when interacting with materials.