waves

1. Introduction
to Waves
Exploring the types
of waves and their
properties

2. Think
About It
How does your voice travel
from your mouth to your
friend's ears when you are
having a conversation?

3. Answer Key
When you speak, your
vocal cords vibrate,
producing sound waves
that move through the air
as compressions and
rarefactions.
Think About It
These sound waves reach
your friend's ears, causing
their eardrums to vibrate,
which their brain interprets
as sound.
Your voice creates sound
waves, which are
vibrations that travel
through the air.

4. KUD’s
K
U
D
Waves: Longitudinal and
transverse waves
A wave is a disturbance that carries
energy without transporting matter.
Waves can be classified depending on
the direction of propagation of the wave
as longitudinal and transverse waves.
Classify the waves as mechanical or
electromagnetic and transverse or
longitudinal, based on the
descriptions of the propagation of the
wave.

5. Electromagnetic Waves
Waves
Waves are disturbances that
carry energy from one place
to another.
Mechanical Waves
Mechanical waves, e.g., sound waves,
require a medium (particles) to travel
through. Sound and water waves are
examples of mechanical waves.
They do not require a medium to travel
through and can travel through a
vacuum. Visible light, radio waves, and
gamma rays are some examples of
electromagnetic waves.

6. rarefaction
compression
Longitudinal
Mechanical waves are
generally categorised into two
main types: longitudinal and
transverse waves.
Longitudinal Waves
Vibrations occur parallel to the
direction the wave travels
Have regions of compression and
rarefaction moving through the medium
direction of wave
propagation
direction of vibration
PUSHING A SLINKY BACKWARDS AND FORWARDS
PRODUCES A LONGITUDINAL WAVE.
MECHANICAL WAVES:

7. rarefaction
Longitudinal
MECHANICAL WAVES: A sound wave is a longitudinal wave. It is
produced when the air surrounding a
vibrating object also vibrates.
The air particles produce a series of
compressions and rarefactions, which then
travel and enter the receiver’s ear.
SOUND TRAVELS THROUGH THE VIBRATION OF AIR PARTICLES.
compression

8. In transverse waves, the
vibrations occur at right angles
to the wave’s direction.
Only the energy, not the
particles, is transferred
through the medium.
direction of wave
propagation
direction of vibration
Transverse
MECHANICAL WAVES:
SHAKING A ROPE UP AND DOWN PRODUCES A
TRANSVERSE WAVE.

9. Electromagnetic Waves
Electromagnetic waves are
transverse waves. It is characterised
by oscillating electric and magnetic
fields at right angles to the direction
of wave travel. These waves travel at
a speed of 3.0 × 10 m/s in a vacuum.
The electromagnetic spectrum can be
divided into seven groups: radio wave,
microwave, infrared light, visible light,
ultraviolet light, x-ray, and gamma ray.
Radio Microwave Infrared Gamma ray
X-ray
Ultraviolet
Visible
The division between some
categories are distinct, but
some bands overlap (e.g.,
infrared, visible, and ultraviolet)
8

10. mechanical wave
electromagnetic wave
longitudinal wave
electromagnetic wave
Learning
Check
During an earthquake, P-waves (or primary
waves) travel the fastest. It can travel through
any type of material and leaves a trail of
compressions and rarefactions through the
medium. What type of wave are P-waves?
A
B
C
D

11. Learning Check
Answer Key
undisturbed medium
compression
rarefaction
P-waves, or primary waves, are
mechanical waves because they
require a medium (solid, liquid, or gas) to
propagate.
Since they create a series of
rarefactions and compressions, the
vibration of the particles in the medium
is in the same direction as wave
propagation. Thus, P-waves fall under
longitudinal waves.
direction of wave propagation

12. crest
through
rest or
equilibrium
position
The undisturbed position of the
particles if they do not vibrate
Otherwise known as the peak,
the highest point of a wave
Parts of a Wave
The lowest point of a wave
Crest
Trough
Rest or Equilibrium Position
direction of wave
propagation

13. amplitude
Amplitude
It is the maximum disturbance
from the crest of the wave
from its rest position. It
represents the wave's height.
The unit for amplitude (A) is
metres (m).
PARTS OF A WAVE:
direction of
wave travel

14. one wavelength
Wavelength
It is a set distance that
represents the full cycle of a
wave. It can be measured from
crest to crest, from trough to
trough, or any two consecutive
points in the wave cycle.
The unit for wavelength
(λ, Greek letter lambda) is
metres (m).
PARTS OF A WAVE:
direction of
wave travel

15. low frequency
high frequency
Frequency
It is the number of waves
passing a specific point per
second.
The unit of frequency is hertz
(Hz), which is equal to 1 cycle
per second (1/s).
PARTS OF A WAVE:

16. compression rarefaction
Longitudinal
Waves
PARTS OF A WAVE:
Amplitude - the closer the particles are in
the area of compression, the greater the
amplitude
Wavelength - the distance between two
consecutive points (between two
compressions or two rarefactions)
Longitudinal waves also exhibit
wavelength and amplitude.
one wavelength

17. A B
Compare these two waves
in terms of frequency,
wavelength, and amplitude.
Learning
Check

18. Answer Key
A B
amplitude amplitude
wavelength wavelength
same amplitude as B
longer wavelength
lower frequency
same amplitude as A
shorter wavelength
higher frequency
Learning Check

19. slower wave faster wave
(longer wavelength,
lower frequency)
(shorter wavelength,
higher frequency)
direction of wave travel
Velocity of a Wave
Wave speed, or velocity, is
defined as the distance a wave
travels per second. We can also
define wave speed as the rate at
which energy is transferred
through a medium.
The unit for wave velocity is
metres per second (m/s).
Medium 1 Medium 2

20. When calculating wave velocity we
use the following formula:
The velocity of a wave depends on its
frequency and wavelength.
wave velocity in m/s = frequency in Hertz or
1/s × wavelength in m
Calculating Velocity of a Wave

21. Calculating
Velocity of a
Wave:
Sample
Problem
While at the beach, you observed that the
waves hit he shore at a frequency of 0.5
waves per second. You also estimated the
distance between the crests of the waves to
be 2 metres.
What is the velocity of the waves as they
travel towards the shore?

22. v = × 2 m
s
0.5
v = 1 m/s
Here's the information given:
v = f × λ
The wave travels at 1 m/s towards the shore.
Calculating
Velocity of a
Wave:
Sample
Problem
frequency (f) = 0.5 waves per second = 0.5/s
wavelength (λ) = 2 m
Now, we plug these values into the formula:

23. Bats use sound waves to detect
insects. Suppose a bat sends out a
100-kHz sound wave at a speed of
343 m/s. What is the wavelength of
the sound wave?
Learning
Check

24. f = 100 kHz = 100,000 Hz or 100,000/s
v = 343 m/s
Given:
Find:
λ = ?
Equation:
v = fλ λ =
f
v
Learning Check Answer Key
Solution:
λ =
100,000/s
343 m/s
λ =
100,000/s
343 m/s
λ = 0.00343 m
The sound wave produced by the bat
has a wavelength of 0.00343 m or
0.343 cm.

25. Waves can be grouped as mechanical
and electromagnetic waves. In terms of
propagation, waves can be grouped as
transverse or longitudinal.
Types of Waves
Waves have amplitude, wavelength,
frequency, and velocity. Changes in
one property can affect the other
features.
Parts of a Wave
Summary
It is a disturbance that transfers
energy.
Wave
To calculate the velocity of a wave,
multiply the frequency with the
wavelength (v = fλ).
Velocity of a Wave