Light and matter

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  1. Light and Matter
  2. Transmission of light through matter
  3. Spectrum of light
  4. Colors by addition
  5. Colors by subtraction Dye Vs. Pigment
  6. Formation of colors in Thin Films
  7. Polarization
  1. Give the reason why would you choose a window shade that is translucent or opaque.
    1. What color do you add to green light to obtain white light?
      1. What primary pigment colors must be mixed to get blue?
        1. What color will a yellow tennis ball appear when is illuminated by
          1. White light
          2. Green and red light
          3. Blue
          1. What would be the result of passing a beam of light through polarizing filter?
            1. Can sound waves be polarized?
              Topic Notes

              In this lesson, we will learn:

              • Transmission of light through different materials
              • Formation of spectrum of light
              • Additive color process
              • Colors by subtraction
              • Formation of color by light, pigments, and dyes
              • Polarization of light


              • Transparent materials: Transmit light waves without distorting images (glass, air)
              • Translucent materials: Transmit light waves but objects can not be see clearly (frosted light bulbs)
              • Opaque: Transmit NO light but absorbs and reflects all light incident upon them (wood, brick)
              • Spectrum: When a narrow beam of light passes though a prism, rainbow of different colors can be seen
              Light and Matter

              • Additive color process (RGB): The additive mixture of blue, green, and red light produces white light.
              Light and Matter

              • Primary colors: red, green, blue
              • Secondary colors: The primary colors are mixed by pairs to produce secondary colors;
              • Yellow (red + green), Cyan (blue + green), Magenta (blue + red)
              Light and Matter

              • Complementary colors: Secondary colors of light, when combined with the primary color, produces white light.
              • Cyan is complementary to red
              • Magenta is complementary to green
              • Yellow is complementary to blue

              • Colors by Subtraction

              Dye Vs. Pigment
              • Dye: A molecule that absorbs certain wavelengths of light, and transmit or reflects others
              • Example: Tomato is red because it reflects red and absorbs green and blue lights.
              • Pigment: A colored material that absorbs a certain colors and transmits or reflects others. Pigment particles are larger than a molecule and can be seen with a microscope.

              Primary Pigment Vs. Secondary Pigment
              • Primary Pigment: A pigment that absorbs only ONE primary color from white light and reflects the other two. (yellow pigment absorbs blue and reflects green and red)
              • Secondary Pigment: A pigment that absorbs TWO primary colors and reflects one. (red absorbs green and blue, green absorbs red and blue, blue absorbs red and green)
              Light and Matter

              Formation of colors in Thin Films

              • Thin-film interference: Spectrum of colors produced by a soap bubble or by the oily film on water. Colors formation is the result of constructive and destructive interference of light waves.
              Light and Matter

              Polarization of light
              • Polarization: Using polaroid material, the direction of vibrating light waves can be modified from many directions to ONLY one specific direction.
              • Polarizer: The material through which light get polarized (polarizing filter)
              Light and Matter