What are Waves?
Building Science Champions
In thought
• On a separate sheet of paper, write a
paragraph about how surfers are able to use
waves for their sport.
Objectives
• Define waves and identify what causes them
• Identify and compare the three main types of
waves.
Key Terms
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Wave
Mechanical waves
Medium
Vibration
Transverse wave
Wavelength
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Crest
Trough
Longitudinal wave
Compression
Rarefaction
Surface wave
What are Waves?
• Wave – is a disturbance
that transfers energy
from one place to
another without
transferring matter.
• All waves spread out
and transfer energy
from the source of the
energy
What is the
energy source
of these
waves?
Raindrops
In which direction is the light
transferred from the candle?
In all directions
Mechanical Waves
• A mechanical wave can only travel through matter
• Mechanical waves can travel through a solid, liquid or
gas
• Mechanical waves cannot travel through a vacuum
• Medium – a material which a wave can travel through
• Two types of mechanical waves – transverse and
longitudinal
• Vibration – is a repeated back-and-forth or up-anddown motion
Transverse Wave
• Transverse wave – is a wave in which the
disturbance is perpendicular to the direction
the wave travels
Draw the picture
and label the parts
of the transverse
wave with the
words from the
next slide
Parts of a Transverse Wave (LIGHT)
• Crest – highest points on a transverse wave
• Trough – the lowest point on a transverse wave
• Rest position – when no disturbance or vibration
is present
• Direction of disturbance can be up-and-down or
side-to-side
• Direction of travel is the direction the wave
travels from the energy source
• Wavelength – from crest to crest or trough to
trough
Transverse Wave
Longitudinal Wave(sound)
• Longitudinal wave – makes the particles in a
medium move parallel to the direction that
the wave travels
Draw the picture
of the longitudinal
wave and label the
wave with the
words from the
next slide
Parts of a Longitudinal Wave
• Compressions – the regions of a longitudinal
wave where the particles in the medium are
closest together
• Rarefactions – the regions of a longitudinal
wave where the particles in the medium are
the farthest apart
• Wavelength – from compression to
compression
Longitudinal Wave
Surface Waves
• Surface waves – combinations of transverse and
longitudinal waves
• Surface waves occur at the surface between 2
mediums, such as water and air
• When waves pass through water, water moves up
and down, like transverse waves on a rope. The
water moves back and forth in the direction the
wave is traveling, like the coils on a spring. Unlike
a spring water does not compress.
Vibrations and Mechanical Waves
• Vibrating objects, such as beating a drum or
strumming a guitar, are the sources of energy
that produce a mechanical wave
• Each vibration makes a wave
• After an object stops vibrating, waves
continue to move
• Water waves are a combination of transverse
and longitudinal waves
Seismic Waves
• Seismic waves are produced when parts of
Earth’s upper layers move along a fault
Electromagnetic Waves
• Electromagnetic wave – is a wave that can travel through
empty space (vacuum) and through matter
• The type of electromagnetic waves given off by an object
depends mainly on the temperature of the object
• Infrared and visible light carry the sun’s radiant energy
Draw the
electromagnetic
spectrum
Review
• There are three types of waves
• Waves are created by energy
References
• Anderson, M. et all (2012) Physical Science.
McGraw-Hill: Columbus
• Frank, D.V et al (2001). Physical Science.
Prentice Hall: New Jersey