Transcript Electromagnetic Spectrum.ppt

Electromagnetic Spectrum
Energy is Quantized!
Quantized = quantity = specific measured amount
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Hypothesized by Max Planck
energy produced by atoms can only have certain values
only distinct lines are seen in element line spectra
can only exist at certain wavelengths.
White Light
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Is composed of different
colors that can be
separated by a prism
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Water acts as a prism for
sunlight, giving the effect of
a rainbow
Sources of white light
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Sun
Regular (incandescent) light
bulbs
Electromagnetic (EM) Radiation
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form of energy
speed of light (3.0 x 108 m/s)
Photons - Wave and particle
electric and a magnetic field
Ex. visible light and X-rays
Blue light
high Energy
short wavelength
longer frequency
Red light
lower Energy
long wavelength
short frequency
Wavelength (λ)
– The distance between two corresponding points on a
wave
– Units are same as length - m, or commonly nm (109 m)
Figure 7.5
• Frequency (ν)
– number of wave cycles that move through a point in
space in 1 s
– hertz (Hz)
– same as inverse seconds (1/s)
Frequency & Wavelength
• inversely proportional
– i.e. as one increases the other decreases
c = λν
c = speed of light (3.0 x 108 m/s)
λ = wavelength (in meters)
ν = frequency (in Hz)
• Which has the greater wavelength the red light or the
green light?
• Which has a greater frequency,?
Figure 7.7
Photons – waves and particles
Energy of a photon
– directly proportional to the frequency
Ephoton = hν
– inversely proportional to the wavelength
Ephoton = hc/
Ephoton = (in Joules)
h = Planck’s constant (6.626 x 10-34 Js)
ν = frequency (in Hz)
wavelength in meters