waves and modern physics - university of rochesterbadolato/phy_123/resources_files/...waves and...
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Waves and Modern Physics PHY 123 - Spring 2012
Prof. Antonio Badolato ���Office: BL 158
Email: [email protected]
Course Web Site http://www.pas.rochester.edu/~badolato/PHY_123/PHY_123.html
Recitations:
Waves and Modern Physics, PHY 123 (Spring 2012)
Monday: 3.25 - 5.25 Imran (HYLAN 202), Tuesday: 3.25 - 5.25 Andrew (HYLAN 206),
4.50 - 7.50 Josh (B&L 270),
6:15 - 8.15 Andrew (B&L 269), Wednesday: 6.15 - 8.15 Andrew (B&L 315).
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
Office Hours:
Waves and Modern Physics, PHY 123 (Spring 2012)
Chapter 15 Wave Motion
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 Characteris.cs of Wave Mo.on
• Amplitude, A
• Wavelength, λ • Frequency, f and period, • Wave velocity,
15-1 Characteristics of Sinusoidal (or Harmonic)Wave Motion
T =1f=2πω
Wave velocity v = λ f = λT
= λω2π
Waves can move over large distances, but the medium itself has only a limited movement, oscillating about an equilibrium point as in SHM.
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:
15-2 Types of Waves: Transverse and Longitudinal
Generation of longitudinal waves: Acoustic 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.
15-‐2 General Waves
Transverse waves traveling through the body of the Earth: so-called S-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.
15-‐2 General Waves
Longitudinal waves traveling through the body of the Earth: so-called P-waves
Surface waves are waves that travel along the boundary between two media (like water waves).
15-‐2 General Waves
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
15– 2 Wave velocity
The velocity of a longitudinal wave depends on the elastic restoring force of the medium and on the mass density.
or E is the elastic modulus B is the bulk modulus ρ is the density