Light & EM Spectrum

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  • Bill Nye Video – 3 parts on light & colour http://www.youtube.com/watch?v=KvOs_RBjLOk&feature=PlayList&p=34CAF189A5C0F7B9&playnext_from=PL&index=0&playnext=1 http://www.youtube.com/watch?v=bPyWooEpwXw&feature=PlayList&p=34CAF189A5C0F7B9&playnext_from=PL&playnext=1&index=1 http://www.youtube.com/watch?v=LjMvgPAyuqo&feature=PlayList&p=34CAF189A5C0F7B9&playnext_from=PL&playnext=2&index=2
  • http://www.youtube.com/watch?v=KvOs_RBjLOk&feature=PlayList&p=34CAF189A5C0F7B9&playnext_from=PL&index=0&playnext=1 http://www.youtube.com/watch?v=gtgBHsSzCPE&feature=related (also part 1) http://www.youtube.com/watch?v=bPyWooEpwXw&feature=PlayList&p=34CAF189A5C0F7B9&playnext_from=PL&playnext=1&index=1 http://www.youtube.com/watch?v=LjMvgPAyuqo&feature=PlayList&p=34CAF189A5C0F7B9&playnext_from=PL&playnext=2&index=2
  • http://www.youtube.com/watch?v=KvOs_RBjLOk&feature=PlayList&p=34CAF189A5C0F7B9&playnext_from=PL&index=0&playnext=1 http://www.youtube.com/watch?v=bPyWooEpwXw&feature=PlayList&p=34CAF189A5C0F7B9&playnext_from=PL&playnext=1&index=1 http://www.youtube.com/watch?v=bPyWooEpwXw (also part 2) http://www.youtube.com/watch?v=LjMvgPAyuqo&feature=PlayList&p=34CAF189A5C0F7B9&playnext_from=PL&playnext=2&index=2
  • Light & EM Spectrum

    1. 1. Properties of Light Light travels at high speeds 3 x 108 m/s 300,000 km/s 1.08 x 1011 km/h 108 billion km/h
    2. 2. Properties of LightLight travels in straight lines
    3. 3. Heat and electricity require a medium for transmission.Particles in a physical substance carry the energy being transmitted. Properties of Light
    4. 4. Transfer of Heat of Energy http://cookwilkie11.wikis.birmingham.k12.mi.us/file/view/Convection-Conduction.jpg/275567456/Convection-Conduction.jpg
    5. 5. Conduction• The process by which heat or electricity is directly transmitted through a substance• Conditions: – a difference of temperature or electrical potential between adjoining regions – without movement of the material• Some examples of conduction: – sound waves – transmission of impulses along nerves
    6. 6. Convection• Movement of molecules within fluids – Transmission of heat in a fluid or gas by the circulation of currents• Fluids: – liquids, gases – Can not be solids• Vertical movement of heat and moisture – Hotter, less dense materials rise – colder, denser material to sink under the influence of gravity• Example: Weather patterns due to updrafts and downdrafts in an unstable air mass http://globalmicrowave.org/content/atmosphericl_convection.jpg
    7. 7. http://www.ux1.eiu.edu/~cfjps/1400/FIG07_006.jpg
    8. 8. http://3.bp.blogspot.com/-ZSVl3YFwDDo/Tycy3SXjXkI/AAAAAAAAAD4/t1XEXbaznOw/s1600/cond_conv_rad_small.jpg
    9. 9. Properties of Light Unlike heat or electricity, light can travel through space without any medium.
    10. 10. Light WavesLight energy travels in waves.Waves are vibrations thattransfer energy from place toplace without matter beingtransferred. http://www.bbc.co.uk/schools/gcsebitesize/science/aqa/radiation/anintroductiontowavesrev1.shtml
    11. 11. Light WavesLight has an electric and magnetic fieldLight is an electromagnetic waveLight transfers energy through electromagnetic radiationElectromagnetic radiation is a method of transferring energy by vibrating electric and magnetic fields
    12. 12. Properties of Waves Wavelength Amplitude Amplitude WavelengthIn our discussion of the changes in wavelength oflight waves, we will assume a constant amplitude.
    13. 13. Electromagnetic Spectrum http://www.kollewin.com/blog/electromagnetic-spectrum/
    14. 14. http://mynasadata.larc.nasa.gov/images/EM_Spectrum3-new.jpg
    15. 15. Electromagnetic Spectrum
    16. 16. Electromagnetic SpectrumThe shorter the wavelength…• Higher frequency• Higher energyAnimation of wavelength and frequency relationship •http://www.bbc.co.uk/schools/gcsebitesize/science/aqa/radiation/anintroductiontowavesrev2.shtml
    17. 17. Electromagnetic Spectrum Application http://ebookbrowse.com/sura-electromagnetic-spectrum-full-chart-pdf-d14713735
    18. 18. Radio Spectrum (9 Hz – 275 GHz) Frequency Allocations in Canada (2007) Divided into frequency bands, each with characteristics peculiar to it which determine the appropriate usage. Each band has been allocated by international agreement at a World Radiocommunication Conference (WRC) to one or more service or usage. After WRC, Industry Canada allocates specific frequency bands to satisfy domestic communications requirements.For better details see original Government of Canada document: http://www.ic.gc.ca/eic/site/smt-gst.nsf/vwapj/spectallocation-08.pdf/$FILE/spectallocation-08.pdf
    19. 19. Visible Spectrum• Although light is a visible form of energy, most of the light energy that surrounds us is invisible• Humans can only detect light within a very narrow range of wavelengths (~400-700 nm)• The range of light waves that we can see is known as the visible spectrum
    20. 20. Visible Spectrum http://www.astro.virginia.edu/~rsl4v/PSC/Images/em.jpg
    21. 21. Visible Spectrum• Colours we see correspond to a specific wavelength on the electromagnetic spectrum• Colours are what makes up the visible spectrum ROY G BIV
    22. 22. ColourAdditive Colour Subtractive Theory Colour Theory (for LIGHT) (for PIGMENT)
    23. 23. Additive Colour TheoryWhite light is composed of different colours (wavelengths) of light
    24. 24. Prism• In a vacuum, each wavelength of light travels at the same speed• A prism will slow down each wavelength of light at different rates – Red light (longest wavelength, least energetic) is slowed the least – Violet light (shortest wavelength, most energetic) is slowed the most• When wavelengths of light travel at different speeds, they will be visible separately into their individual colours
    25. 25. Additive Colour TheoryIt is possible to produce white light bycombining the three primary colours oflight: • Red • Green • Blue
    26. 26. Additive Colour Theory If you mix two primary colours together, you will make a secondary colour Secondary Colours of light: • Magenta • Yellow • Cyan
    27. 27. Primary Colours of Light make up a computer monitor
    28. 28. Primary & Secondary Colours Additive Subtractive (all light sources) (all pigments)
    29. 29. Subtractive Colour Theory Primary Colours: • Cyan • Magenta • Yellow Secondary Colours: • Red • Green • Blue
    30. 30. Printer Ink
    31. 31. Subtractive Colour TheoryColoured objects absorb somewavelengths (colours) of light andreflect the rest which is what we see.
    32. 32. Colour Theory• White light is the combination of all the colours reflected into our eyes• Colours detected by the eye are due to wavelengths being reflected off the object• Colours undetected by the eye are due to wavelengths being absorbed by the object• White objects reflect all colours• Black objects absorb all colours
    33. 33. Bill Nye Video Light & ColourQuestions for part 1 (0:50-2:45, 3:45-4:12, 5:15-end)http://www.youtube.com/watch?v=gtgBHsSzCPE&feature=related• What is white light?• What does a prism do to white light?• Why can’t a prism break up red light into other colours like it can do to white light?• What gives fruits and vegetables all their different colours?• What colour(s) is the skin of a red apple absorbing?• What colour is the skin of a red apple reflecting?• What happens to all the colours of white light when it hits a black object ?• What is the function of pigments in paints?• How do you get black paint?• Why does mixing all the colours of paint give you black instead of white when white light is a mixture of all colours?See next slide for 2 more questions from part 3 of video
    34. 34. Bill Nye Video Light & ColourQuestions for part 3 (0-1:45) http://www.youtube.com/watch? v=bPyWooEpwXw&feature=PlayList&p=34CAF189A5C0F7B9&playnext_from=PL&playnext=1&index=1• Why is the sky blue?• Why does water look blue?Optional for part 3: clip on Crayola follows 1:45Optional for your viewing interest: part 2 http://www.youtube.com/watch? v=bPyWooEpwXw&feature=PlayList&p=34CAF189A5C0F7B9&playnext_from=PL&pla ynext=1&index=1• information on neon lights and lasers
    35. 35. Multiwavelength
    36. 36. Multiwavelength• Visible light provides only limited information about our universe.• Information from the ‘invisible’ parts of the electromagnetic spectrum has provided a lot of exciting and surprising discoveries.• Gallery of astronomical images of objects in multiple wavelengths of the EM spectrum• http://coolcosmos.ipac.caltech.edu/cosmic_classroom/multiwavelength_• Slideshow of the sun in different wavelengths compared to hearing Beethoven’s 9th in different frequencies• http://ccnmtl.columbia.edu/projects/helfand/• Multiwavelength Universe Poster• http://teachspacescience.org/graphics/pdf/10000729.pdf

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