What is a wave?
A wave is defined as the propagation
of a disturbance that carries the
energy and momentum away from
the source of disturbance.
Wave is a disturbance or variation which travels through
a medium.
The medium through which the wave travels may
experience some local oscillations as the wave passes,
but the particles in the medium do not travel with the
wave.
 A group of people jumps up and
sits back down, some nearby
people see them and they jump
up, some people further away
follow suit and pretty soon you
have a wave traveling around the
stadium.
 The wave is the disturbance
(people jumping up and sitting
back down), and it travels
around the stadium.
 However, none of the individual
people the stadium are carried
around with the wave as it travels
- they all remain at their seats.
1. Mechanical wave
2.Electromagnetic wave
Mechanical wave
Mechanical wave is defined as a
disturbance that travels through
particles of the medium to transfer
energy.
Sound
waves
Water
waves
Seismic
waves
Mechanical
wave
Waves in
spring
Waves on
string /
rope
Mechanical Waves
All mechanical waves require:
 Some source of disturbance
 A medium that can be disturbed
 A mechanism to transfer the disturbance from
one point to the next point along the medium.
Almost all waves are
mechanical waves,
except EM waves
Types of wave
Transverse Wave
Longitudinal
Waves
Transverse Waves
 Is a wave in which the direction of vibrations
of particle is perpendicular to the direction of
the wave propagation.
 E.g.: water waves, waves in string.
Longitudinal Waves
 Is a wave in which the direction of vibrations of the
particle is parallel to the direction of the wave
propagation.
 E.g.: sound waves, waves in spring
Surface Waves
 Surface waves such as water waves combine
longitudinal and transverse wave movement.
Properties of the Wave
 Wavelength, λ: the horizontal distance between any
two successive equivalent points on the wave.
 Amplitude, A: the highest point on the wave pattern
 Period, T: the time required for the wave to travel a
distance of one wavelength.
 Unit is second.
 Frequency, f : f=1/T.
 The frequency is measured in cycles per second or
hertz (Hz).
Properties of the Wave
 Wave speed, v: The distance traveled by a wave profile
per unit time.
 v=λ/T= λf
Example
y (cm)
40 cm
15 cm
x (cm)
A wave traveling in the positive x direction as pictured above.
Find the amplitude, wavelength, period, and speed of wave if it
has a frequency of 8.0 Hz.
Solution
 The amplitude and wavelength can be read directly from the
figure.
A = 15 cm = 0.15 m
λ = 40 cm = 0.40 m
 The period of the wave is
T
1
f
1
8.0 Hz
0.13 s
 Wave speed is
v
f
(8.0 Hz )( 0.40 m)
3.2ms
1