11.1 What is light

• heat energy transferred by conduction/convection = requires transmission medium   * medium = physical substance thru which energy can be transferred
• light travels thru vacccum of outer space → thus does not need medium
• light transferred through radiation   * radiation: method of energy transfer that doesn’t need medium; energy travels at the speed of light
• predicted in 1801 that electricity + magnetisim ⇒ chains traveling thru space
• resulting EM wave does not need a medium, and travels @ speed of light
• Electromagnetic Wave: a wave has both electric + magentic parts, and does not need a medium. it travels @ speed of light, and varies in frequency and types of radiation
• visible light: EM waves that human eyes can detect
• EM spectrum: classification of EM waves from low to high energy
• examples of radio waves: radio, tv signals, radar, phones
• examples of microwaves: microwaves, GPS
• examples of infrared: remotes, keeping food warm, heat detection
• examples of visible light: human vision, lighting, rainbows
• examples of UV light: sunburns, “black” light, also increases risk of skin cancer
• examples of X-Rays: cancer treatment, medical imaging, takes photos of galaxies
• examples of gamma rays: cancer treatment

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