HONR228Q Notes section c:

  • Electromagnetic Waves and the Electromagnetic Spectrum

    1. Electromagnetic Waves

      1. Do waves require a medium?
        1. Experiment
          1. DEMO H1-01: BELL IN VACUUM
        2. Conclusions
          1. Sound waves require a medium but light waves do not.
          2. Historical inquiry as to sound as wave or particle.
          3. Invention of centrifugal vacuum pump mechanism.
          4. Conclusion: EM waves propagate in vacuum.
      2. Are waves transverse or longitudinal?
        1. Experiments
          1. DEMO M7-05: ROPE AND COOKIE COOLERS
          2. DEMO M7-01: MICROWAVES POLARIZATION
          3. DEMO M7-03: POLAROIDS AND GOOSENECK LAMP
          4. DEMO K8-01: ELECTROMAGNETIC WAVE - MODEL
          5. DEMO K8-05: ELECTROMAGNETIC PLANE WAVE MODEL
        2. Conclusions
          1. Light waves are transverse waves
          2. Sound waves are longitudinal waves
          3. Rope wave analog to crossed polaroids.
          4. Accurate representation of interaction between polaroid material and light waves
          5. Crossed polaroids stop transverse EM wave
      3. Speeds of sound and light waves
        1. Experiments
          1. DEMO H1-22: SPEED OF SOUND USING PULSES
          2. DEMO K8-04: SPEED OF LIGHT
        2. Conclusions
          1. The speed of light is about 1,000,000 times greater than the speed of sound.
          2. The speed of light is approximately 300,000,000 meters per second.

    2. The Electromagnetic Spectrum

      1. EM Spectrum (refer to slide) in order of increasing frequency, decreasing wavelength, or increasing photon energy
        1. Low-frequency EM waves
        2. AM Radio
        3. VHF TV
        4. FM Radio (between TV channels 6 and 7)
        5. UHF TV
        6. Microwaves
        7. Infrared
        8. Visible light
          1. Red, Orange, Yellow, Green, Cyan, Blue, Violet
        9. Ultraviolet
        10. X-rays (originate from inner electron transitions)
        11. Gamma-rays (originate from nuclear transitions)
      2. Demonstration of members of the electromagnetic spectrum
        1. DEMO N1-05: SPECTRA VISIBLE AND INVISIBLE
          1. Demonstrates IR, Visible, and UV
        2. DEMO P3-31: X-RAY TUBE
        3. Orbiting Frog Blog: Earth and Friends in Multiple Wavelengths
          1. Photographs using various electromagnetic waves.
      3. Assignment of all frequencies of the electromagnetic spectrum
        1. U.S. assignments made by the Federal Communicationns Commission
        2. Covers 3 kHz to 300 GHz, with color diagrams and notes
        3. PDF file (requires Adobe Acrobat reader)
        4. Some interesting recent applications:
          1. Digital Mobile Phone (frequency bands around 850MHz and 1950MHz)
          2. Global Positioning System (GPS): OnStar, etc., L1 = 1575.42 MHz and L2 = 1227.6 MHz
          3. Satellite Radio: ~2.325-2.345 GHz.
      4. Television Frequency Table
        1. VHF and UHF channels listed
        2. Cable TV frequencies given
        3. Web site supported by consortium of commercial interests

    3. Radiation Related Terms, from the Idaho State University Radiation Information Network

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