Transcript 5_1 Light and Quantized Energyx

standard: 1i, 1j
terms: p.117
article: 144
mastering concept: 146(30-38)
practice prblems: 121(1-4), 124(5-6
lab write up: 125
home lab:954 #5
Homework
cornell notes: 5.1
sec. assessment: 126 (7-11)
mastering problems: 147(65-76)
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New Terms
• Electromagnetic radiation
– A form of energy that has wavelike behavior
• Wavelength
– The shortest distance between equivalent points
on a wave
• Frequency
– The # of waves that pass through a given point per
second
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relationship
• Wavelength vs. frequency
– As wavelength increase, frequency decrease
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• Electromagnetic spectrum
– All forms of electromagnetic radiation
• Quantum
– The minimum amount of energy that can be
gained or lost by an atom
• Planck’s constant
– Value used to determine the energy of a quantum
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• Photoelectric effect
– phenomenon where electrons are emitted from a
metal’s surface when light of a certain frequency
shines on the surface.
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Sunlight takes about 8 minutes 17 seconds to
travel the average distance from the surface of
the Sun to the Earth.
Exact values: 299,792,458 meters per second
Calculating wavelength of an EM wave
Radio waves are used to transmit information on
various channels. What is the wavelength of a
radio wave having the frequency of 5.40 X 1010
Hz?
V = 5.40 X 1010 Hz 1/s or s-1
C = 3.00 X 108 m/s
3.00 Exp or EE 8 ÷
λ=?m
5.40 Exp or EE 10 =
C = λV
λ = C/V = 3.00 X 108 m/s
5.40 X 1010 1/s
= 5.5 x 10-3 m
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Practice Problems: P. 121 (1-4)
1. What is the frequency of green light, which
has a wavelength of 4.9 x 10-7m?
2. An X ray has wavelength of 1.15 x 10-10m.
What is its frequency?
3. What is the speed of an electromagnetic wave
that has a frequency of 7.8 x 106 Hz?
4. A popular radio station broadcasts with a
frequency of 94.7 MHz. What is the
wavelength of the broadcast? (1MHz = 106 Hz)
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Calculating wavelength of an EM wave
1. What is the frequency of green light, which
has a wavelength of 4.9 x 10-7m?
C = 3.00 X 108 m/s
λ = 4.9 x 10-7m
3.00 Exp or EE 8 ÷
V=?
4.90 Exp or EE -/+ 7 =
C = λV
V = C/λ = 3.00 X 108 m/s
4.9 x 10-7m
= 6.12 x 1014 1/s
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Calculating wavelength of an EM wave
2. An X ray has wavelength of 1.15 x 10-10m.
What is its frequency?
C = 3.00 X 108 m/s
λ = 1.15 x 10-10m
V=?
3.00 Exp or EE 8 ÷
1.15 Exp or EE -/+ 10 =
C = λV
V = C/λ = 3.00 X 108 m/s
1.15 x 10-10m
= 2.61 x 1018 1/s
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Your Turn...
3. What is the speed of an electromagnetic wave
that has a frequency of 7.8 x 106 Hz?
C = 3.00 X 108 m/s
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Your Turn...
4. A popular radio station broadcasts with a
frequency of 94.7 MHz. What is the wavelength
of the broadcast? (1MHz = 106 Hz)
C = 3.00 X 108 m/s
V = 94.7 MHz (106 Hz = 1MHz )=9.47 x 107 s-1
λ=?
3.00 Exp or EE 8 ÷
9.47 Exp or EE -/+ 7 =
C = λV
λ= C/V = 3.00 X 108 m/s
9.47 x 107 s-1
= 3.17 m
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Flame Test Lab 125
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• Gamma
• Radio
Visible EM Radiation
• The human eye can detect EM radiation
within a 400 nm – 750 nm range.
• This radiation is processed and interpreted
by our brains as color.
Elemen Color
t
λ
(nm)
Barium Ba
Yellow
590
Copper Cu
Green/blu 520
e
Sodium Na
orange
Calcium
Ca
Red/
620
Orange
λ (m)
V =C/λ E = hv
1m=109nm C=3x108 h=6.626x 10-34
630
6.2x10-7
4.8x1014
3.2x10-19
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Element Color λ
(nm)
Lithium
Red
Sodium
Yellow
Potassium
violet
Calcium
Red/
620
λ (m)
V =C/λ E = hv
1m=109nm C=3x108 h=6.626x 10-34
6.2x10-7
4.8x1014
3.2x10-19
Orange
Strontium
Bright
red
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Practice Problems: 124(5-6)
5. What is the energy of each of the following
types of radiation?
a. 6.32 x 1020 s-1
b. 9.50 x 1013 Hz
c. 1.05 x 1016 s-1
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Practice Problems: 124(5-6)
5. What is the energy of each of the following
types of radiation? 6.32 x 1020 s-1
v = 6.32 x 1020 s-1
h = 6.626 X 10-34 J.s
?J
6.32 Exp or EE 20 x
6.626 Exp or EE -/+ 34=
Ephoton = hV
Ephoton = 6.32 x 1020 s-1 (6.626 X 10-34 J.s)
= 4.19 x 10-13 J
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Practice Problems: 124(5-6)
a. 5. What is the energy of each of the
following types of radiation? 9.50 x 1013 Hz
v = 9.50 x 1013 s-1
1/s or s-1
h = 6.626 X 10-34 J.s
?J
9.50 Exp or EE 13x
6.626 Exp or EE -/+ 34=
Ephoton = hV
Ephoton = 9.50 x 1013 s-1 (6.626 X 10-34 J.s)
= 6.29 x 10-20 J
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Practice Problems: 124(5-6)
6. Use Figure 5-5 to determine the types of radiation
described in problem 5
a. 6.32 x 1020 s-1
b. 9.50 x 1013 Hz
c. 1.05 x 1016 s-1
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