Waves and Modern Physics
PHY 123 - Spring 2012
Prof. Antonio Badolato Office: BL 158
Email: badolato@pas.rochester.edu
Course Web Site
http://www.pas.rochester.edu/~badolato/PHY_123/PHY_123.html Waves and Modern Physics, PHY 123 (Spring 2012)
Recitations:
Monday:
3.25 - 5.25 Imran
Tuesday:
3.25 - 5.25 Andrew (HYLAN 206),
4.50 - 7.50 Josh
(HYLAN 202),
(B&L 270),
6:15 - 8.15 Andrew (B&L 269),
Wednesday: 6.15 - 8.15 Andrew (B&L 315).
Waves and Modern Physics, PHY 123 (Spring 2012)
Office Hours:
Prof. Antonio Badolato:
Wednesday, 1:45 p.m. - 2:45 p.m. room BL 158
TA Andrew Vigoren:
Thursday,
3:30 p.m. - 4:30 p.m,
room BL 324
Chapter 15
Wave Motion
15-­‐1 Characteris.cs of Wave Mo.on All types of traveling waves transport energy.
A single wave pulse can
be generated by a
vibration. It is transmitted
through internal forces in
the medium.
Continuous waves start
with vibrations, too. If the
vibration is SHM, then the
wave will be sinusoidal.
15-1 Characteristics of Sinusoidal (or
Harmonic)Wave Motion
•  Amplitude,
A
•  Wavelength, λ
1 2π
•  Frequency, f and period, T = =
f
ω
•  Wave velocity,
Wave velocity λ
ω
v=λ f = =λ
T
2π
Waves can move over large distances, but the
medium itself has only a limited movement,
oscillating about an equilibrium point as in SHM. 15-2 Types of Waves:
Transverse and Longitudinal
The motion of particles in a wave can be either
perpendicular to the wave direction (transverse)
or parallel to it (longitudinal).
15-2 Types of Waves: Transverse
and Longitudinal
Sound waves are longitudinal waves:
Generation of longitudinal waves: Acoustic Waves
15-­‐2 General Waves Waves can be a formed by a combination of
longitudinal and transverse waves (like earthquakes
waves). Both types can travel through solid material,
but only longitudinal waves can propagate through a
fluid—in the transverse direction, a fluid has no
restoring force.
Transverse waves
traveling through the
body of the Earth:
so-called S-waves
15-­‐2 General Waves Waves can be a formed by a combination of
longitudinal and transverse waves (like earthquakes
waves). Both types can travel through solid material,
but only longitudinal waves can propagate through a
fluid—in the transverse direction, a fluid has no
restoring force.
Longitudinal waves
traveling through the
body of the Earth:
so-called P-waves
15-­‐2 General Waves Surface waves are waves that travel along the
boundary between two media (like water waves).
15– 2 Wave velocity The velocity of a transverse wave on a
cord is given by:
As expected, the
velocity increases
when the tension
increases, and
decreases when the
mass increases.
15– 2 Wave velocity The velocity of a longitudinal wave depends
on the elastic restoring force of the medium
and on the mass density.
E is the elastic modulus
or
B is the bulk modulus
ρ is the density