Graphics Programs Reference
In-Depth Information
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Both ends of this scale are, of course, outside the visual perception range of hu-
mans.
The second aspect of this measuring system was frequency, and it was used to
check how many times in a given second the peak of an electromagnetic wave
passed a fixed point. The measurement value given to this movement was hertz.
The range can be measured from 50-60 Hz on the low end, which is the frequency
of AC electricity, all the way up to greater than 1019 Hz, which would take us into
gamma ray territory.
Sitting right in between these two extremes, however, is a range of wave types that
we refer to as the visible light spectrum, which occupies only about one thousandth
of a percent of the entire electromagnetic range. At one end of this visible spectrum,
we have red light that has both the longest wavelength and the lowest frequency,
making it the least dangerous radiation type for humans. This is why we are able to
use infrared signals to control devices such as TV remote controls.
At the other end of the scale comes violet light that has both the shortest wavelength
and the highest frequency. Once you get just a little higher on the scale, into ultravi-
olet, you dip into the part of the electromagnetic spectrum that can start to be quite
harmful to humans should they have intense or prolonged exposure to it.
Although all of this work seemed to indicate that light had ultimately been accepted
to travel as a wave form, the debate over its nature wasn't quite done yet. Just as
everything seemed to be settled, along came some guy named Einstein in 1905 and
put the cat among the pigeons by embracing the idea of wave-particle duality in light.
Einstein's unusual approach was to accept the model of light behavior that best fit
the work he was currently doing. He basically concluded that as light was clearly
an immensely complex phenomenon in terms of its behavior, he was quite happy to
accept that it could (as the evidence seemed to suggest) behave in a dual wave-
particle manner. It seemed then that Newton wasn't, strictly speaking, wrong after all.
Current scientific thinking also readily accepts this dual nature in the behavior of light.
When it is travelling away from a source, light is accepted to be working as an elec-
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