Chap-2: Waves and Sound

1
Chap-2 Waves and Sound
Wave is a traveling disturbance. Wave carries
energy from place to place. There are two basic
types of waves Transverse waves and
longitudinal waves.
2
Transverse waves
A transverse wave is one in which the disturbance
is perpendicular to the direction of travel of
the wave. Examples Light wave, waves on a guitar
string.
3
Longitudinal Waves
Longitudinal wave is one in which the disturbance
is parallel to the line of travel of the wave.
Example Sound wave in air is a longitudinal
wave.
4
Water Waves
Water waves are partly transverse and
longitudinal.
5
Light and Electromagnetic waves
Electric and magnetic fields fluctuating together
can form a propagating electromagnetic wave.
Differences between sound and light
Bell-in-Vacuum Demonstration.
6
Periodic Waves
http//www.physicsclassroom.com/class/sound/u11l1c
.cfm
Periodic waves are waves that repeat.
7
Amplitude, Wavelength, and Period
The amplitude, A is the maximum disturbance. The
wavelength, ?  is the horizontal length of one
cycle of the wave. The period, T is the time
required for one complete up/down cycle of the
wave.
8
Wave Speed
9
2.2 Fundamental Properties of Waves

1. Huygenss principle
2. Superposition
3. Inverse square law
4. Polarization

The above first three phenomena apply to both
longitudinal and transverse waves. Polarization
is unique to transverse waves, for example light.

10
WAVE FRONTS AND RAYS
The angle between a wave front and a ray is 900.
11
Spherical and plane wave fronts
12
Wave fronts
Circular wave fronts (a) produced by a vibrating
ball, and linear wave fronts (b) produced by a
vibrating bar in a ripple tank. The lines in both
represent the crests of successive waves.