Visible and ultraviolet light

• How does visible light appear different colors?

  It depends on the wavelength
• What is the order of colors in visible light?

  Red, orange, yellow, green, blue, indigo, violet
• What does the phrase "boy G bit" help to remember?

  The order of colors in visible light
• How do optical fibers transmit light?

  By reflecting light at the surface
• What materials are used for optical fibers?

  Thin glass or plastic fibers
• Why must materials used in optical fibers reflect light?

  To prevent absorption of light
• What type of reflection is required in optical fibers?

  Specular reflection
• What is the advantage of optical fibers over copper wires?

  They transmit more information with less distortion
• Where does ultraviolet radiation fall on the spectrum?

  After violet
• What is a common source of ultraviolet radiation?

  The Sun
• What can ultraviolet radiation from the Sun cause?

  Suntans and sunburns
• How can we generate ultraviolet radiation artificially?

  Using sun beds
• What is fluorescence?

  Absorption of UV light and emission of visible light
• Why do fluorescent paints appear bright?

  They emit visible light
• How do fluorescent lights work?

  They convert UV light into visible light
• What is a benefit of using fluorescent bulbs?

  They are energy efficient
• How do security pens utilize ultraviolet radiation?

  They mark property invisible until UV light shines
• How are UV features used in passports and banknotes?

  To make them harder to copy
• What is one use of UV radiation in water treatment?

  To sterilize water by destroying microorganisms
• What are the main uses of visible and ultraviolet light?

  • Communication using optical fibers
  • Fluorescence in paints and lights
  • Security features in documents
  • Sterilization of water
• What are the differences between visible light and ultraviolet light?

  • Visible light: Can be seen, varies in color
  • Ultraviolet light: Invisible, shorter wavelength than visible light