Download Electromagnetic Waves (EMS) PPT notes

The entire range of all the
various kinds of radiation;
light (or the visible
spectrum) comprises just
one small segment of this
much broader spectrum.
Frequency decreases………..
Wavelength increases………….
The range of electromagnetic
waves that can be detected by
the human eye.
 The
wavelengths of visible light are in the
middle range of wavelengths/frequencies
of electromagnetic waves.
 The longer the wavelength, the lower the
energy of the wave is.
A Human’s Vision is called
Visible Light
The human eye reacts to different energies and
frequencies of light so that different colors are
seen.
 o Higher frequencies (shorter wavelengths) are
perceived as colors toward the blue-violet range
and have higher energy.
 o Lower frequencies (longer wavelengths) are
perceived as colors toward the orange-red
range and have lower energy.

What do dogs and cats see?

Us……………………. Them
 The
range of electromagnetic
waves with frequencies lower
than red on the visible
spectrum, thereby having
longer wavelengths and less
energy than red wavelengths.
Infrared Waves

Detects heat being
released from a
house.
Infrared Radiation
The image on the left shows an optical view
of a star forming region. The image on the
right is the same region in infrared. The
infrared observations penetrate the
obscuring cloud to reveal many new
details.
Gemini

All objects emit infrared radiation, and hotter
objects emit more infrared radiation than cooler
objects.

Heat energy is transmitted by infrared radiation.
When objects absorb infrared radiation, they
become warmer.

Since atmospheric water vapor absorbs, or "soaks-up", infrared radiation, this was a
very important consideration when selecting the sites for the Gemini telescopes.
More Infrared Images
The image below on the left is a man
holding a lit match. Compare the heat of
his glasses to his face and hands.
On the right: Where is the cat the coldest?

The
range of electromagnetic
waves with frequencies higher
than violet on the visible
spectrum, thereby having
shorter wavelengths and more
energy than violet
wavelengths.
The
image below is of the
Sun taken at an Extreme
Ultraviolet wavelength.
Because of the high energy of ultraviolet radiation, too
much exposure is damaging to the eyes and skin.
A Bee’s Vision is in Ultra-Violet
 Computer
simulation: How bees
perceive the world v. Humans
A - Flower seen through the human eye.
B – Flower seen through bee’s eye.
A
B
More bees vs.
humans
What’s so bad about UV waves?

Can cause skin damage – Solar Keratoses
Eye Anatomy – open up your
Glencoe book to p. 519
Color Fatigue Effect
 Fatigue
in cone cells due to
staring at a certain color for a
prolonged period of time.
Blind Spot





Close your right eye.
With your left eye, look at the +.
You should see the red dot in your peripheral
vision.
Keep looking at the + with your left eye.
The red dot will move from the left to the
right and disappear and reappear as the dot
moves into and out of your blind spot.