UV and visible 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
• How is visible light used for communication?

  Through optical fibers transmitting light pulses
• What are optical fibers made of?

  Thin glass or plastic fibers
• How do optical fibers transmit light?

  By reflecting light at the surface
• What is required for effective light transmission in optical fibers?

  Materials that totally reflect light
• What type of reflection is necessary for optical fibers?

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

  They transmit more information with less distortion
• What is a common source of ultraviolet radiation?

  The Sun
• What is one use of ultraviolet radiation?

  To give a suntan or sunburn
• 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 light after absorbing UV light
• How do fluorescent lights work?

  They generate UV radiation absorbed by phosphor
• What is a benefit of using fluorescent bulbs?

  They are energy efficient
• How can UV radiation be used for security?

  With special pens to mark property
• What is one application of UV radiation in security?

  Marking passports and banknotes
• How does UV radiation help in detecting forgeries?

  It makes markings visible under UV light
• How does UV radiation sterilize water?

  By destroying microorganisms