Light
Light moves in waves and travels at the constant speed of approximately 3x10^8 m/s. Nothing can ever reach this speed.
The Electromagnetic Spectrum
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The Electromagnetic Spectrum shows the frequencies and wavelengths for various types of radiation. Radiation is energy that transmitted in the form of waves or particles. The range of this electromagnetic radiation is known as light. An electromagnetic wave is composed of two parts: the amplitude which is the "brightness" of the light, and the wavelength which is related to the color. The wavelength of the wave is also the angle of which the wave is vibrating, known as polarization.

Radio Waves - waves with the lowest frequencies and the longest wavelenghts of the waves in the Electromagnetic Spectrum
Types of Radio Waves:
ELF (Extra Low Frequency) waves
  • frequency ranges from 1Hz to 1KHz
  • used for submarine communication and in our own brain waves!
VLF (Very Low Frequency) waves
  • frequency ranges from 1KHz to 300KHz
  • used in communication between ships at sea and is produced in lightning
  • INSPIRE VLF Radio Receiver: measures VLF waves in the weather to detect storms
AM (Amplitude Modulation) Radio waves
  • frequency ranges from 300KHz to 1.5 MHz
  • used in your radio!
Short Wave Radio waves
  • frequency ranges from 1.5 MHz to 30MHz
  • used in your radio!
  • used by truckers - citizen band radio or HAM radio
  • these waves bounce off of the ionosphere and back to earth so...sometime you can hear radio stations from VERY far away if you dial into the set frequency
VHF (very high frequency) waves
  • frequency ranges from 30MHz to 300MHz
  • wavelength is about the same as a man's height
  • used for FM (frequency modulation) radio
  • basic TV (channels you get for free) uses these
UHF (ultra high frequency) waves
  • frequency ranges from 300MHz to 3000MHz or 3GHz
  • used in cell phones, bluetooth, wi-fi, cable TV and HDTV

Microwaves -
  • overlap with UHF waves in ranges of frequency
  • used in microwave ovens!
    • waves move back and forth causing the water to move - this kinetic energy results in heat!
  • microwaves are not really harmful to your body
  • used in radars

Infrared -
  • frequency ranges from 300GHz to 30THz
  • used in remote controls! - they send signals via infrared
  • uses heat
Visible Light -
  • frequency ranges from 30THz to 100THz
  • only light we can see!
external image em%20spectrum.gif
  • wavelengths only range from 700nm (nanometers) to 400nm
  • based off of seven colors: red, orange, yellow, green, blue, indigo, and violet

UltraViolet -
  • frequency ranges from 100THz to 10^17Hz
  • chloraflora carbons : create holes in our ozone layer and allow more UV rays to come into our atmosphere
  • UV can damage skin - it does not penetrate the skin, but it does 'mess up' the molecules
X-Rays -
  • otherwise known as ionizin radiation
  • knocks the electrons off of atoms
  • shares the same frequency range as Gamma Rays
  • emitted by black holes

Here is a neat video on Xrays and black holes!
http://www.space.com/common/media/video/player.php?videoRef=080623-black-hole






This video explains a little more on how the black holes emit xrays and how they are detected. Detecting these xrays can be a struggle! But the talented scientists came up with great solutions to detect these xrays. The scientists also learned much more about black holes and how they affect the stars around them. Enjoy!

Gamma Rays -
  • results of neuclear interactions
  • highest freqency waves on the spectrum


Structure of the eye and how we see color:

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The eye is a visual organ that detects light and sends impulses through the optic nerve to the brain in order to let the image be deciphered. Color, whose definition is "the psychological and physiological response to light waves a a specific frequency or set of frequencies interacting with the eye", is picked up in the eye by the retina. There are two types of sensory cells in the retina: the rods and the cones. The rods in the eye are associated with light intensity, so they are optimal for vision in the dark. But cones react to different frequencies, more specific those of red, green, and blue light. The green cones are the most sensitive, covering the largest range of frequencies, while the blue and red cones are receptive to less frequencies. The frequencies of light that the cones receive also overlap each other, allowing for a greater variety of colors that we see. Color is produced by what an object does not absorb. Whatever color it does not absorb, we see the color of that object as the color of light that was not absorbed. For instance, if a shirt reflects red light, then we see the shirt as red.

Primary Colors of Light, Pigment, and Filters:
The primary colors of light, the ones with the frequencies that are received by our cones, are red, green, and blue. These colors, when added together, create white light, while the absence of light creates the "color" black. These colors overlap each other, allowing for different colors, or the Additive Secondary Colors, which are cyan, yellow, and magenta, to exist. They are the complimentary colors of light, but they are the primary colors of pigments and filters. The primary colors of pigments and filters together form black, and the absence of these colors creates white.The filters let through only what color it is, so if a filter is cyan it lets in green and blue light out of the broad spectrum of light.
The primary colors of light:
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The primary colors of pigments and filters:
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