Electromagnetic Energy

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Electromagnetic Energy

• Topic 5
• Energy in Earth Processes

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energy

• The ability to do work

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Electromagnetic energy

• The type of energy given off in transverse waves
  by all matter above absolute zero
• Each kind of e-mag energy has its own wavelength

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wavelength
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Electromagnetic spectrum

• A model showing all the forms of e-mag energy

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• Page 14 ESRT
• Visible light can be broken down into colors by
  wavelength.

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The hotter the object the more e-mag energy it
gives off.
high
Amount of e-mag energy given off
low
hot
cold
Temperature of Object
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The hotter the object, the shorter the wavelength
given off.
long
Wavelength
short
hot
cold
Temperature of Object
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E-mag waves can be
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The characteristics of a surface determine the
amount and kind of e-mag energy absorbed.

• Color - dark absorb more/reflect less
• Texture (rough/smooth) - rough absorbs more
• Luster/reflectivity (shiny/dull) - dull absorbs
  more

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source

• Region with a higher concentration of energy than
  its surroundings

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Sink (no, not the kitchen kind)

• Region with a lower energy concentration than its
  surroundings
• Energy always flows from a source to sink.

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Energy is transferred across interfaces.
source
sink
50C
30C
The sink absorbs more than it radiates. temperatu
re increases
The source radiates more than it
absorbs. temperature decreases
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Energy is transferred across interfaces.
The 2 objects absorb the same amount that they
radiate. temperature is constant This is called
dynamic equilibrium or radiative balance.
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Energy Transformations

• When e-mag energy of short wavelength is
  absorbed, it can be reradiated at longer
  wavelengths.
• A material that is a good absorber of
  electromagnetic energy is a good radiator of
  electromagnetic energy.