Science Notes by Ahmet Arduc - What is Light


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What is Light
Science Notes by Ahmet Arduc -

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Science Notes by Ahmet Arduc - What is Light

  1. 1. What is Light by Ahmet Arduc –
  2. 2. [Visible*] Light is a type of electromagnetic radiation within a certain portion of the electromagnetic spectrum. Electromagnetic radiation (EM radiation or EMR) (consists of electromagnetic waves) is the radiant energy released by certain electromagnetic processes. It is a kind of radiation including visible light, radio waves, gamma rays, and X-rays, in which electric and magnetic fields vary simultaneously. * which is visible to the human eye and is responsible for the sense of sight.
  3. 3. The electromagnetic waves that compose electromagnetic radiation can be imagined as a self-propagating transverse oscillating wave of electric and magnetic fields. This diagram shows a plane linearly polarized EMR wave propagating from left to right. The electric field is in a vertical plane and the magnetic field in a horizontal plane. The electric and magnetic fields in EMR waves are always in phase and at 90 degrees to each other.
  4. 4. This 3D animation shows a plane linearly polarized wave propagating from left to right. Note that the electric and magnetic fields in such a wave are in-phase with each other, reaching minima and maxima together
  5. 5. The colors that make up white light are called visible spectrum. Color Wavelength (nm) Red 780 – 622 = 158 nm Orange 622 – 597 = 25 nm Yellow 597 – 577 = 20 nm Green 577 - 492 Blue 492 - 455 Violet 455 - 390
  6. 6. • Infrared radiation (IR) is used in some television controls, night vision photography, sea surface temp imaging.
  7. 7. • Ultraviolet radiation (UV) that seeps through the atmosphere is known to cause skin cancer. Frogs are sensitive to UV so they are monitored to see the presence of holes in the Ozone.
  8. 8. The relative wavelengths of the electromagnetic waves of three different colors of light (red, green, and blue) with a distance scale in micrometers (1 meter is 1,000,000 micrometer) along the x-axis.
  9. 9. The main source of light on Earth is the Sun. About 49 % of the electromagnetic waves emitted by the Sun are infrared waves, about 43 % are visible light, and about 7 % are ultraviolet waves.
  10. 10. Some ancient philosophers (like plato and pythagoras) believed that light traveled from our eyes to the objects we look at, rather than from the objects to our eyes.
  11. 11. Abu Ali Hasan Ibn Al-Haytham, c. 965 – c. 1040 CE
  12. 12. Is light a particle or a wave - Colm Kelleher
  13. 13. Light and Plant Growth What kind of materials does light pass through? You will watch a video shows that our reality doesn't look the same in a different spectrum of light. Things which are opaque in visible light are sometimes totally transparent in the (near) infrared light. In the video a Delamax 950 nanometer filter is used. The human eye is sensitive from about 390 to 700 nm. Transparency in IR spectrum (950nm)