5. Material makeup. The amount of IR energy emitted by objects is affected by the material
makeup of the objects, shape of the objects, finish or texture, and whether the objects are light
or dark in tone (color). The size of the object has no effect on the amount of IR energy it can
emit, reflect or absorb. This will be covered in more detail later. All objects with a temperature
above absolute zero have an ability to emit, reflect, and absorb energy.
a.
Emitted energy is generated by molecular activity.
b.
Reflected energy is reflected from an outside source.
c.
Absorbed energy is emitted by an outside source and absorbed by an object.
6. IR energy. The primary source of IR on the earth is the sun. IR energy, like visible light,
which is also on the electromagnetic spectrum, travels at the speed of light (186,000 miles or
300,000 kilometers (km) per second). It travels in all directions, and like visible light, its
intensity or strength will decrease the further it travels away from its source. You can
mathematically determine the diminishing energy of a given area using the inverse square law.
For example, the amount of energy available for detection at 2,000 feet (ft) would be 1/4th of
that at 1,000 ft. The amount of energy available for detection at 3,000 ft would be 1/9th of that
of 1,000 ft, and at 4,000 ft the amount of energy available for detection would be 1/16th of that
at 1,000 ft. IR energy can be refracted, reflected, focused, measured, and recorded. You
should be familiar with all these terms.
a.
Refracted light passes through a prism and each color is separated to create a
rainbow-like effect. This is exactly what happens when the atmosphere is heavy with
moisture. The moisture refracts the light coming from the sun, separates it into its various
colors, and a rainbow Is formed.
b.
Reflected light occurs with any mirrorlike apparatus.
c.
Focused light can be concentrated on one spot. An example is using a lens to
concentrate the sun's light on a piece of paper or wood to make it ignite. A laser beam is
another example.
d.
Measured light. Refer to Figure 1-2, electromagnetic frequency spectrum.
e.
Recorded light. Refer to Figure 1-2, electromagnetic frequency spectrum.
7. Electromagnetic frequency spectrum. Electromagnetic energy has been defined in terms
of its specific wavelength. The various wavelengths have been placed on a graduated scale
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