Section 14­1.notebook
April 09, 2012
Most of us have seen light waves, there are more waves than the "white light" that we see. The spectrum of visible lights consist of R.O.Y.G.B.I.V.
Light waves also include more than visible light.
Electromagnetic Wave ­ is a transverse wave consisting of oscillating electric and magnetic fields at right angles to each other.
In electromagnetic wave theory light is a wave composed of oscillating electric and magnetic fields. The fields are perpendicular to the direction in which the wave moves. The waves are distinguished by different frequencies and wavelengths which accounts for different colors.
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Section 14­1.notebook
April 09, 2012
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Section 14­1.notebook
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Electromagnetic Spectrum
Classification Range
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Radio Waves
λ > 30 cm , f < 1.0 x 10 Hz
Microwaves
30 cm > λ > 1 mm, 1.0 x 109 Hz < f < 3.0 x 1011 Hz
Infared Waves
1mm > λ > 700 nm, 3.0 x 1011 Hz < f < 4.3 x 1014 Hz Visible Light
700 nm > λ > 400 nm, 4.3 x 1014 Hz < f < 7.5 x 1014 Hz
Ultraviolet Light
400 nm > λ > 60 nm, 7.5 x 1014 Hz < f < 5.0 x 1015 Hz
X Rays
60 nm > λ > 10­4 nm, 5.0 x 1015 Hz < f < 3.0 x 1021 Hz
Gamma Rays
0.1 nm > λ > 10­5 nm, 3.0 x 1018 Hz < f < 3.0 x 1022 Hz
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Section 14­1.notebook
April 09, 2012
Electromagnetic waves travel at the speed of light. The speed of light in a vaccum travels at 2.99792458 x 108 m/s. The speed of light in air travels slower at 2.99709 x 108 m/s.
The value of speed of light to be used is 3.00 x 108 m/s.
Wave Speed Equation
c = f λ
speed of light = frequency x wavelength
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Section 14­1.notebook
April 09, 2012
There is a difference in the brightness from a light that has a 100 W bulb versus a 25 W bulb. This also applies to the distance that you are from the source of the light. As you increase the distance from the source it is proportional to the actual brightness divided by the square of the distance betweeen the source and the observer. Example if you are twice the distance from the source ¼ of the light falls on the source. 3 times the distance is 1/9 of the brightness.
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Section 14­1.notebook
April 09, 2012
Practice 14A ­ all
Section Review ­ all
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