Transcript 7.25 x 10 20 Hz

Chapter 4
The Electromagnetic Spectrum
Part 1
Visible Light
• Part of the Electromagnetic Spectrum
All types of electromagnetic energy
move in waves.
• Light and sound move
by waves.
• Light moves at
3 x 108 m/s
• Sound moves at
340 m/s
• 1 mile = 1609 m
All types of electromagnetic energy
move in waves.
• Light moves at
3 x 108 m/s
• Sound moves at
340 m/s
• Is sound a form of
electromagnetic
radiation?
Electromagnetic Waves
• Properties of waves include speed, frequency
and wavelength
• All electromagnetic waves including light travel at
a speed of 3 x 108 m/s.
Wavelength ()
Measured in
units of length:
m, nm, Aº
Frequency ()
Measured in cycles/second = hertz (Hz)
Visible Light
Electromagnetic Radiation
• For all waves
• = c
• c = the speed of light = 3.00 x 108 m/s
A photon of red light has a wavelength of
665 nm. What is the frequency of this light?
A photon of red light has a wavelength of
665 nm. What is the frequency of this light?
• 665 nm = 665 x 10-9 m
A photon of red light has a wavelength of
665 nm. What is the frequency of this light?
• 665 nm = 665 x 10-9 m
• c=•
A photon of red light has a wavelength of
665 nm. What is the frequency of this light?
• 665 nm = 665 x 10-9 m
• c=•
•  = c ÷  = 3.00 x 108 m/s ÷ 665 x 10-9 m
A photon of red light has a wavelength of
665 nm. What is the frequency of this light?
•
•
•
•
665 nm = 665 x 10-9 m
c=•
 = c ÷  = 3.00 x 108 m/s ÷ 665 x 10-9 m
 = 4.511278 x 1014/s or Hz
A photon of red light has a wavelength of
665 nm. What is the frequency of this light?
•
•
•
•
•
665 nm = 665 x 10-9 m
c=•
 = c ÷  = 3.00 x 108 m/s ÷ 665 x 10-9 m
 = 4.511278 x 1014/s or Hz
 = 4.51 x 1014/s or Hz
An x-ray has a frequency of 7.25 x 1020 Hz.
What is the wavelength?
An x-ray has a frequency of 7.25 x 1020 Hz.
What is the wavelength?
• 7.25 x 1020 Hz = 7.25 x 1020/s
An x-ray has a frequency of 7.25 x 1020 Hz.
What is the wavelength?
• 7.25 x 1020 Hz = 7.25 x 1020/s
• c=•
An x-ray has a frequency of 7.25 x 1020 Hz.
What is the wavelength?
• 7.25 x 1020 Hz = 7.25 x 1020/s
• c=•
•  = c ÷  = 3.00 x 108 m/s ÷ 7.25 x 1020/s
An x-ray has a frequency of 7.25 x 1020 Hz.
What is the wavelength?
•
•
•
•
7.25 x 1020 Hz = 7.25 x 1020/s
c=•
 = c ÷  = 3.00 x 108 m/s ÷ 7.25 x 1020/s
 = 4.137931 x 10-13 m
An x-ray has a frequency of 7.25 x 1020 Hz.
What is the wavelength?
•
•
•
•
•
7.25 x 1020 Hz = 7.25 x 1020/s
c=•
 = c ÷  = 3.00 x 108 m/s ÷ 7.25 x 1020/s
 = 4.137931 x 10-13 m
 = 4.14 x 10-13 m
Energy of Waves
Energy of Electromagnetic
Radiation
• For all waves:
E = h•
h = 6.63 x 10
J • s or J/Hz
-34
A photon of red light has a wavelength of
665 nm. What is the energy of this light?
A photon of red light has a wavelength of
665 nm. What is the energy of this light?
•
•
•
•
•
665 nm = 665 x 10-9 m
c=•
 = c ÷  = 3.00 x 108 m/s ÷ 665 x 10-9 m
 = 4.511278 x 1014/s or Hz
 = 4.51 x 1014/s or Hz
A photon of red light has a wavelength of
665 nm. What is the energy of this light?
•
•
•
•
•
•
665 nm = 665 x 10-9 m
c=•
 = c ÷  = 3.00 x 108 m/s ÷ 665 x 10-9 m
 = 4.511278 x 1014/s or Hz
 = 4.51 x 1014/s or Hz
E = h •  = (6.63 x 10-34 J • s)(4.51 x 1014/s)
A photon of red light has a wavelength of
665 nm. What is the energy of this light?
•
•
•
•
•
•
•
665 nm = 665 x 10-9 m
c=•
 = c ÷  = 3.00 x 108 m/s ÷ 665 x 10-9 m
 = 4.511278 x 1014/s or Hz
 = 4.51 x 1014/s or Hz
E = h •  = (6.63 x 10-34 J • s)(4.51 x 1014/s)
E = 2.99013 x 10-19 J
A photon of red light has a wavelength of
665 nm. What is the energy of this light?
•
•
•
•
•
•
•
665 nm = 665 x 10-9 m
c=•
 = c ÷  = 3.00 x 108 m/s ÷ 665 x 10-9 m
 = 4.511278 x 1014/s or Hz
 = 4.51 x 1014/s or Hz
E = h •  = (6.63 x 10-34 J • s)(4.51 x 1014/s)
E = 2.99013 x 10-19 J = 2.99 x 10-19 J
An x-ray has a frequency of 7.25 x 1020 Hz.
What is its energy?
An x-ray has a frequency of 7.25 x 1020 Hz.
What is it’s energy?
• E = h •  = (6.63 x 10-34 J/Hz)(7.25 x 1020Hz)
An x-ray has a frequency of 7.25 x 1020 Hz.
What is it’s energy?
• E = h •  = (6.63 x 10-34 J/Hz)(7.25 x 1020Hz)
• E = 4.80675 x 10-13 J
An x-ray has a frequency of 7.25 x 1020 Hz.
What is it’s energy?
• E = h •  = (6.63 x 10-34 J/Hz)(7.25 x 1020Hz)
• E = 4.80675 x 10-13 J
• E = 4.81 x 10-13 J
wavelength, frequency and energy
Red Light
X-ray
•  = 665 x 10-9 m
•  = 4.51 x 1014 Hz
• E = 2.99 x 10-19 J
•  = 4.14 x 10-13 m
•  = 7.25 x 1020 Hz
• E = 4.81 x 10-13 J
Wavelength, frequency and energy
• Wavelength and frequency have an
indirect relationship.
• Energy and frequency have a direct
relationship.
• Electromagnetic radiation with a shorter
wavelength will have a higher frequency
and higher energy.
• Electromagnetic radiation with a longer
wavelength will have a lower frequency
and lower energy.
Homework
• Chapter 4: Worksheet 2 (due in two days)