Waves and their Applications in
Technologies for Information
Transfer in Lego Mindstorms
NGSS MS-PS4
What do I need to know about
Waves?
I must:
1) Know how our sensors use
waves to provide input
information about the
environment.
2) Identify the parts of a wave.
3) Contrast a light wave with a
sound wave.
a.
b.
How are they similar?
How do they travel?
4) Explain what causes “sound”
What is a wave?
Wave – A disturbance that
propagates through space and
time, usually with transference
of energy.
Examples:
Light, Water (mechanical),
and Sound
Video: (00:00-09:08)
Waves; Sound and Electromagnetism
What is a wave?
A simple wave has a
repeating pattern with a
specific wavelength,
frequency, and
amplitude. (MS-PS4-1)
 Wavelength – The distance
between two sequential
crests, troughs or nodes of a
wave.
 Amplitude – The maximum
disturbance in a medium
during one wave cycle.
 Frequency – The number of
occurrences of a wave per
unit time. (Measured in Hertz)
Sound Waves
 Sound waves are called
compression or
longitudinal waves
 They compress particles
which transfer energy
along a path.
 The wavelength is the
distance between areas
of compression
 Video: Sound Wave Properties
(0:00 – 3:40)
Wavelength
Compression Waves can be
represented as transverse waves
using an oscilloscope
Sound Waves
 Video: Sound Waves
 Compression waves require a
medium to travel through.
Wavelength
 Gas (air) allows compression wave
energy to travel to your ear.
(Human Hearing)
 Slowest Speed
 Liquids (water) – Whale
communication
 Medium Speed
 Solids (rock) – Earthquakes
 Fastest Speed
 Video: Sound in a Bell Jar
 Video: What Does a Sound Wave Look Like?
Compression (Longitudinal) Waves
can be represented as transverse
waves using an oscilloscope
Sound Waves
 The frequency of a sound
wave is determined by the
number of compressions
passing a given point per
second.
 High frequency sound
waves = High Pitch
 Low frequency sound
waves = Low Pitch
Wavelength
Wavelength
The Sound Sensor
Our Sound Sensor:
1) Detects the amplitude
of the input audible
frequencies
(frequencies that we can hear)
2) A threshold must be set to
determine the high and low
values.
3) Because the sound sensor
detects amplitude (volume),
the frequency (pitch) doesn’t
matter.
threshold
The Ultrasonic Sensor
Our Ultrasonic Sensor:
1)
2)
3)
Uses sound waves at
frequencies beyond hearing.
(ultrasonic waves)
It sends ultrasonic pulses out,
they bounce off objects and
return to the sensor.
The time that it takes to return
to the sensor is used to
determine the distance an
obstacle is from the sensor.
a.
This is the same process
bats use during
echolocation
Video: (09:08-14:05)
Waves; Sound and Electromagnetism
Light Waves
Video: What is Light?
1) Light is made of
electromagnetic waves.
2) They are transverse
waves. (not like sound)
3) They are absorbed and
reflected by objects
a. Video: Light Absorption
and Reflection
Light Waves
Light Waves
1) Colors of visible light are
determined by the
frequency of the light
waves.
2) Electromagnetic waves
exist outside of our ability
to detect and these are
known as the Ultraviolet
and Infrared regions of the
electromagnetic spectrum.
a.
Ultra –”on the far side of, beyond”
b.
Infra – “below”
Light Waves
Light Waves
1) Do not need a medium (solid,
liquid or gas) to travel through.
a.
It can travel through the
vacuum of space
i.
2)
Sunlight travels to earth.
Changing the medium causes
light wave to reflect (bounce
back) or refract (change
direction)
a.
Video: Reflection and
Refraction of colored light
between Water (liquid) and Air
(gas)
The Light Sensor
Our Light Sensor
1) Can detect ambient light
a.
2)
The natural light of the environment
Can detect reflected light
a.
Sends out a red light.
i.
3)
Visible light in the red frequency.
A threshold must be set to
determine the high and low values
for reflected light.
Different colored surfaces reflect
light differently.
The light sensor detects the
brightness of the light reflected
back to the sensor.
4)
5)
a.
b.
Dark colors absorb more light –
reflect very little.
Light colors reflect a lot of light.
Wrap It Up
1) How do our sensors use waves to provide input
information about the environment.
2) What are the parts of a wave.
3) Contrast a light wave with a sound wave.
a.
b.
How are they similar?
How do they travel?
4) What causes “sound”?
Wrap It Up
1. Energy is transferred from one place to another
through waves.
2. All waves have a wavelength, frequency, and
amplitude.
3. Waves move at different speeds in different materials.
a. Air (gas) = slow
b. Liquid (water) = medium
c. Solid (rock) = fast
Wrap It Up
Sound Waves:
1. Are produced when
objects vibrate.
a. Drum
b. Guitar strings
2. Are longitudinal
(compression) waves.
3. Cannot travel in a vacuum.
a.
Require some sort of
medium to travel through
(Solid, liquid and gas)
a.
Speed changes as the
enter new medium
Light Waves:
1. Are electromagnetic
waves
2. Are transverse waves
3. Are reflected or
refracted (bent)
4. Can travel through a
vacuum.
a. Ex. Sunlight to Earth