DATE ________________
NOTE-026
CHEM 110 (BEAMER)
xNOTES-026:x Light
xxx
xxx
Light and the EM Spectrum
I.
Light

Light
radiation
=

Light can behave both as a
particle

A particle of light is called a
photon
. They are two terms for the same thing!
wave
and a
.
.
Parts of a Wave
II.
Diagram of a Wave
D
A
F
C
E
B

Wavelength
.

Wavelength
is the length between

The symbol for wavelength is

The units for wavelength is

meters
two consecutive, similar points on a wave.
, lower case Greek
lambda
, but is often modified with
.
metric prefixes

A, B, and C
represent correctly marked wavelengths by the definition above.

D, E, and F
represent incorrectly marked wavelengths by the definition above.
.
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DATE ________________
NOTE-026
B.
Frequency
.

Frequency
is the number of
fixed point

The symbol for frequency is

The unit for frequency is


1 second
wavelengths
wavelengths
=
second
s
pass a
.
nu
, lower case
tricky
that
(pronounce “new”).
.
waves
s


1
s
or s-1

Hertz (Hz)
Examples for determining frequency

Starting at Time 0, mark off each consecutive wavelength.
2
1

wavelengths
in

CHEM 110 (BEAMER)
There are
4
full wavelengths in the
3
4
1 second
interval.
 = 4 Hz
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DATE ________________
NOTE-026
CHEM 110 (BEAMER)
Example 2
1s
0s

There are
8
full wavelengths in the
1 second
interval.
 = 8 Hz
Example 3
This would be “2”
1

Caution:

There are
Frequency isn’t always a
1.75
wavelengths in the
+ 0.5
+ 0.25
whole number
1 second
interval.
 = 1.75 Hz
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DATE ________________
II.
NOTE-026
CHEM 110 (BEAMER)
The Electromagnetic Spectrum (EM Spectrum)

Your textbooks call this the
Radiant Energy Spectrum
.

Highest frequency has the
highest energy
.

Shortest wavelength has the
highest energy
.
Nobody calls it this.
Not Drawn To Scale
Lowest 
Highest 
Radio
Microwave
Infrared (IR)
Visible
(ROYGBIV)
Ultraviolet (UV)
X-Ray
Gamma
Cosmic
Longest 

Sample Problems
1)
2)
3)
Shortest 
WOTF (Which of the following) sets of radiation is written in order of highest energy to lowest energy?
A)
IR > Microwaves > X-Rays > Orange
B)
Radio > Green > UV > Cosmic
C)
Gamma > UV > Yellow > X-Ray
D)
Cosmic > Violet > Infrared > Microwave
E)
X-Ray > Gamma > Green > Radio
WOTF (Which of the following) sets is written in order of lowest frequency to highest frequency?
A)
IR > Microwaves > X-Rays > Orange
B)
Radio > Green > UV > Cosmic
C)
Gamma > UV > Yellow > X-Ray
D)
Cosmic > Violet > Infrared > Microwave
E)
X-Ray > Gamma > Green > Radio
Rewrite the following types of radiation in order of shortest wavelength to longest wavelength.
Blue
Infrared
X-Rays
Microwaves
Green
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DATE ________________
NOTE-026
CHEM 110 (BEAMER)
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