Understanding the basic properties of waves.pptx

Introduction to Waves
Prester John

Objectives
 Learn the basic characteristics of waves and use
them to solve simple problems.

What Are Waves?
 A wave is a disturbance that carries energy
through matter or space without transferring
matter.
 Wave Demo

Wave Characteristics
 Amplitude: The
greatest distance from
equilibrium.
 The bigger the
amplitude of the wave,
the more energy the
wave has.

 Crest: The top point of a wave.
 Trough: The bottom point of a wave.

 Wavelength: The shortest distance between
points where the wave pattern repeats itself.
Wavelength
is measured
in meters,
the symbol
is

 Phase: Any two points on a wave that are one or
more whole wavelengths apart are said to be “in
phase”.

 Frequency: Is the number of complete
oscillations a point on that wave makes each
second.
Frequency is
measured in Hertz
(Hz), its unit is

 Speed: The speed or velocity of a wave is how
fast the energy is moved. For most waves, wave
speed does not depend on amplitude, frequency,
or wavelength. Speed depends only on the
medium through which it moves.

 Period: The time it takes a wave to go through
one cycle, or the time it takes a point to go
through one phase of the wave.
 The period of a wave is measured in seconds,
and it’s symbol is “T”.

Example 1
 What is the velocity of a wave that has a
frequency of 250Hz and a wavelength of 1.5m?

Example 2
 How does the speed of a wave change if the
amplitude is increased?
 The speed doesn’t change.
 What is the velocity of a wave that has a
frequency of 100Hz and a wavelength of 2.0m?

Objectives
 Learn how to draw a wave diagram
 Learn about the different types of waves.
 Study, create, and destroy different wave types.

Try these!
 Draw the following waves on the same graph:
1. A wave with an amplitude of 6m and a
wavelength of 3m.
wavelength of 2m.
wavelength of 4m.

Waves transfers energy
but not matter
Recall!

Classification of waves
Waves can be classified based on their characteristics. Some common
types of waves include:
1.Mechanical waves
2.Electromagnetic waves
3.Transverse waves
4.Longitudinal waves
5.Surface waves

Waves
Movement of waves
may or may not require
a medium.

Examples of waves
Water waves
light waves
Sound waves
microwaves

So what’s a medium?
A medium is a channel through
which waves travel. It could be any
form of matter (solid, liquid, or gas!)
 In a water wave, the medium is the water.
 In a sound wave, the medium is the air.
 In an earthquake, the medium is the ground.

Waves that requires a medium to
travel are called mechanical waves
Examples:
Sound waves
Seismic waves
Water waves
1. Mechanical waves

2. Electromagnetic Waves
 Electromagnetic waves do not require a medium
They can travel through space (or vacuum).
 They are mostly caused by disturbances in electric and
magnetic fields.
Examples:
Radio waves
Light waves
Infrared waves
Ultraviolet waves
X-ray
Gamma rays

Question
What happens when waves travel through a medium?
Answer
They transfer energy.
Example
Sound traveling in your ear causes vibration
in your ear
Test yourself

3. Transverse waves
In transverse waves, the direction of wave particle
is perpendicular to the wave direction.
Transverse waves can be modelled by moving one end of a slinky
up and down. Each coil represents a particle.
source moves
up and down
direction of wave
propagation
coils vibrate
up and down

4. Longitudinal waves
In longitudinal waves, each particle oscillates parallel to the
direction of propagation of the wave. There is no vertical
movement.
Longitudinal waves can be modelled by moving one end
of a slinky back and forth. Each coil represents a particle.
source moves
left and right
coils vibrate
left and right
direction of wave

Within longitudinal waves, regions in which the particles
are relatively close together are called compressions, and
regions where they are relatively far apart are called
rarefactions.
Sections of longitudinal waves
compression
rarefaction

Transverse and longitudinal waves

Transverse vs. Longitudinal Waves

The wavelength of a longitudinal wave
can be measured as the distance
between the center of two compressions
or rarefactions.

5. Surface Waves
-These waves occur at the boundary
between two different mediums.
-They can be transverse or longitudinal.
- They move in circular motion
-Example
Ocean waves.

Facts to note!!
Mechanical waves can be transverse,
longitudinal , or surface waves
Electromagnetic waves will only be
transverse.

Checkpoint
1. What is a Transverse wave?
2. What is a Longitudinal wave?

1. What is the wavelength of a sound wave with a frequency
of 50 Hz? (Speed of sound is 342 m/s)
2. A sound wave in a steel rail has a frequency of 620 Hz
and a wavelength of 10.5 m. What is the speed of sound in
steel?
3. Determine the frequency of a microwave 6.0 cm in length.
(A microwave is an electromagnetic wave. It travels
through space at a speed of 3.0 x 10 ^8 m/s)
4. What is the period of the microwave in problem 3?
Word problems

Class Test
1. If a wave is moving toward shore with a velocity of 36
km/h and it has a frequency of 2.5 hertz, what is its
wavelength?
2. If a tuning fork has a frequency of 320 hertz and the
wavelength of the sound it produces is 150 cm, what is the
velocity of the wave.
3. The speed of light in a vacuum is 1.08 x 109
km/h. Red light
has a wavelength of 7 x 10-7
, what is its frequency in a
vacuum?
4. The frequency of violet light is 7.5 x 1014
hertz. What is its
wavelength in a vacuum? (speed of light = 3.0 x 108
m/s.)
5. If a jump rope is shaken fast enough to produce a wave
with a wavelength of 5 x 10-3
km and the crest of the wave

Understanding the basic properties of waves.pptx

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