Electromagnetic Spectrum Flashcards
Highest Point in the wave
Crest
Lowest Point in the wave
Trough
Amplitude
Distance between midpoint and crest/trough
Wavelength
Distance between two identical points on wave
Period
The time it takes for 1 wave to pass a point.
Frequency
The number of waves that pass a point per amount of time.
Does light behave in a dual nature? What as?
Yes, as both
Particles and Waves
What is the fundamental unit of EMS?
Photon
What wavelength do all active systems use?
0.1 - 100cm (microwave region)
How fast do photons move at?
300,000km/h
Lowest Frequency/Longest Wavelength?
Radio Bands/Waves
Upper end of EMS? 2 types?
Whats smaller than that?
Gamma rays and X-rays
Smaller is Ultra Violet
Spectrum of visible light (Blue, Green, Red?
What UMs for each?
- Blue light = 0.4 μm → 0.5 μm
- Green light = 0.5 μm → 0.6 μm
- Red light = 0.6 μm → 0.7 μm
Blackbody, what is it?
A Blackbody is defined as an object that absorbs all incoming radiation and emits all energy at full efficiency for all wavelengths.
All things emit radiation is they are above?
-273C or 0K
Radiance (Mλ) is defined as:
the total amount of energy measured at the sensor representing a point on the ground.
3 different energy-matter interactions?
1) transmittance - some radiation penetrates into certain surface materials such as water;
2) absorption
3) Reflection/scattering
Atmospheric Attenuation
Incoming energy is weakened by atmosphere.
Explain transmittance?
the portion of light that passes though a medium
3 different types of scattering
Releigh scattering = particles smaller than wavelengths
Mei scattering = non-molecular scattering
Non-select scattering = lower part of atmosphere
common effects of non-selective scattering
fog and cloud
Diffuse Reflectors
rough surfaces which reflect uniformly in all directions. These reflectors yield a reflection pattern which is generally uniform.
Specular reflectors
where the angle of reflection is equal to the angle of incidence
Bidirectional Reflectance
- when lots of reflection is occurring around.
What the result?
The result is that the reflectance off one surface is composed of both a diffuse as well as a specular component