Download ElectromagneticSpectrum - Mr-Durands

Good Morning! 7/7/2017
•Starter: What is Light? ( you need to write an
answer for this one)
•Goal: get some understanding of what light is
and the spectrum of electromagnetic waves.
•Today we continue our discussion on Waves,
simply moving into a new area of waves.
First we need to finish the
worksheet from yesterday on
Sound waves.
Link to PPT
We are going to split up and do
the worksheet on the laptops
The rest will be going through a
Powerpoint (.ppt) on the screens.
For those going to the laptops you will be
going to the usual place.
Science Shares Folders  Durand 
then open the word doc.
“EMSpectrumLink”
Light is a crazy thing that we may never
understand, but let me tell you what we
do know.
•Light travels as a wave, a transverse,
Electromagnetic Wave.
•It can behave as a particle
•It travels faster than anything in the
universe!
•It is impossible for us to travel faster than
the speed of light.
The Back Story
Why does light travel so fast?
What are electromagnetic waves?
12.1
Waves and Particles
• The difference between a wave and a particle
might seem obviousa wave is a disturbance
that carries energy, and a particle is a piece of
matter.
• However, in reality the difference is not so
clear.
What are electromagnetic waves?
12.1
Waves and Particles
• In 1887, Heinrich Hertz found that by shining
light on a metal, electrons were ejected from
the metal.
• Hertz found that whether or not electrons
were ejected depended on the frequency of
the light and not the amplitude.
What are electromagnetic waves?
12.1
Waves and Particles
• Because the energy carried by a wave
depends on its amplitude and not its
frequency, this result was mysterious.
• Years later, Albert Einstein provided an
explanationelectromagnetic waves can
behave as a particle, called a photon, whose
energy depends on the frequency of the
waves.
What are electromagnetic waves?
12.1
Particles as Waves
• Because electromagnetic waves could behave
as a particle, others wondered whether matter
could behave as a wave.
• If a beam of electrons were sprayed at two tiny
slits, you might expect that the electrons would
strike only the area behind the slits, like the
spray paint.
What are electromagnetic waves?
12.1
Particles as Waves
• Instead, it was found that the electrons formed
an interference pattern.
• This type of pattern is produced by waves
when they pass through two slits and interfere
with each other.
Particles as Waves
• Water waves
produce an
interference
pattern after
passing through
two openings.
• It is now known
that all particles,
not only
electrons, can
behave like
waves.
Electromagnetic Waves
Believe it or not, you are being “showered”
all the time, not by rain but by waves.
What Is an Electromagnetic Wave?
An electromagnetic wave consists of vibrating
electric and magnetic fields that move through
space at the speed of light.
How do sunglasses work?
An analogy for sunglasses
The Nature of
Electromagnetic Waves
Electromagnetic Waves
Click the Video button to watch a movie about
electromagnetic waves.
Waves of the
Electromagnetic Spectrum
Electromagnetic Waves Activity
Click the Active Art button to open a browser window and
access Active Art about electromagnetic waves.
Waves of the
Electromagnetic Spectrum
What Is the Electromagnetic Spectrum?
The electromagnetic spectrum is the complete range of
electromagnetic waves placed in order of increasing
frequency.
Electromagnetic Waves
Waves of the
Electromagnetic Spectrum
Electromagnetic Spectrum
Click the Video button to watch a movie about
the electromagnetic spectrum.
Please turn in your Worksheet on
Electromagnetic Spectrum
Radio and Television
In AM transmissions, the amplitude of a radio wave is
changed. In FM transmissions, the frequency is changed.
Wireless
Communication
Comparing Frequencies
In the
cellular
phone
system,
cellular
phones
transmit
and
receive
radio
waves that
travel to
the
nearest
tower.