Spring 2016
PHYS 306: Physics of Wave Motion
Jigang Wang
Department of Physics &
Astronomy,
Iowa State University
jgwang@iastate.edu
http://www.public.iastate.edu/~jgwang/PHYS306-2016/
Why Vibrations & Waves?
Electromagnetic waves
Quantum waves
Mechanical waves
Fundamental for energy storage and energy transfer
The Amazing Wave – Laser
Optical
Communication
Laser
Machining
Bar code
scanner
Cosmic MW
background
http://www.laserfest.org
Laser lithography
Medical
Imaging
Laser wake field
particle accelerator
Ubiquitous Phenomena
Periodic & oscillatory motion
Not So Ubiquitous Waves…
White light from white wine
soliton
The Course
• Who: undergraduates in physics and engineering who
want to
(1) Understand fundamentals of vibration and wave
physics, as well as their applications to mechanics,
electromagnetism, materials physics and engineering
(2) Prepare for studying advanced physics/engineering
courses
• Goals
(1) Develop a certain way of thinking and approaching
things
(2) Effective communications
• What is needed:
PHYS 221 & PHYS222 or similar
• Course philosophy
Mechanics
Thermal
Physics
Statistical
Physics
Electricity
&
magnetism
Quantum
mechanics
“The theory of everything”
Cross-cutting models/concepts
Mechanics
Thermal
Physics
Statistical
Physics
Electricity
&
magnetism
Quantum
mechanics
“The attitude ” that can approach everything
Textbooks and Handouts
Handout materials will be drawn from the textbooks, journal
articles and some other book chapters
Course Delivery
Lectures, homework, exams & quizzes
• 11:00 – 12:20 every T/R
• Lecture by Jigang Wang + some demos
• Homework problems: 1-2 problems per week, due
every Thursday (no exception, please)
• In-class quizzes: ~5 minute break during the
lecture
• Midterm exam (in class)
• Final exam
http://www.public.iastate.edu/~jgwang/PHYS306-2016/
Score Breakup
Homework problems: 15%
In-class small quizzes (10) &
recitations (3): 10%
Midterm exam 30%
Final exam: 45%
Total: 100%
A really brief summary of topics
1. Phasor notation
2. Free, damped and forced harmonic oscillations
3. Resonant phenomena
4. AC circuits
5. Coupled oscillators
6. Normal modes
7. Travelling waves
8. Wave equation, impedance
9. Transverse and longitudinal waves
10. Energy transport in waves
11. Reflection and transmission at interfaces
12. Group and phase velocity
13. Dispersion
14. Fourier series and Fourier transforms
1. Prepare the textbook
2. Review the section for vibrations and
waves in PHYS 221 (University Physics)
Simple Harmonic Oscillator
Model systems with periodic & oscillatory motion
E
Basic Elements: (1) inertia, or its equivalent
(2) a displacement, or its equivalent
(3) restoring force for a negative feedback
Simple Harmonic Oscillator
use physics/mechanics to
write equation of motion for
system
restoring force
Inertial force
insert generic trial form of
solution
Fs   s x(t )
d2
Fi  m 2 x(t )  mx(t )
dt
equation of motion
mx(t )  sx(t )  0
x(t )   x(t )  0
2
s

m
find parameter values for
which trial form is a solution
x(t )  a sin(t   )
t
Simple Harmonic Oscillator
A basic literacy in physics
More complex problems
Many-oscillator problem
Anharmonic oscillators
Thermal
Optical
Thermal transport,
optical properties and
polarization of solids
Nonlinear optics,
optical harmonic generation,
Soliton propagation