Uses of EM Waves

• What are some uses of radio waves?

  • Transmit radio signals
  • Transmit terrestrial TV signals
  • Travel long distances before absorption
  • Reflect off the ionosphere for long-distance communication
• Why are radio waves suitable for transmitting signals?

  They can travel long distances before absorption
• What is terrestrial TV received with?

  An aerial
• What phenomenon allows longer wavelength radio waves to spread out between hills?

  Diffraction
• What is the ionosphere?

  A layer of charged particles in the atmosphere
• How do microwaves heat food?

  Water molecules absorb microwave energy
• What is one use of microwaves besides heating food?

  Communicate with satellites
• Why can microwaves pass through the Earth's atmosphere?

  They are not reflected or refracted
• What are some uses of infrared waves?

  • Emitted by electrical heaters
  • Used to cook food in ovens
  • Absorbed by objects to increase temperature
  • Used in infrared cameras for heat loss detection
• How does infrared energy affect room temperature?

  It is absorbed by objects, warming them
• What is a key use of visible light?

  Communication using fiber optics
• What are optical fibers made of?

  Thin strands of glass
• Why can visible light carry a great deal of information?

  It has a short wavelength
• What are some uses of ultraviolet light?

  • Energy-efficient lightbulbs
  • Sun tanning in tanning beds
  • Increases risk of skin cancer
  • Causes premature skin aging
• Why are energy-efficient lightbulbs advantageous?

  They require less energy than normal bulbs
• What is a key use of x-rays?

  Visualizing broken bones
• How do x-rays and gamma rays differ in medical imaging?

  X-rays are absorbed by bones, gamma rays are not
• What is a common use of gamma rays?

  Detecting cancers
• What are the medical applications of x-rays and gamma rays?

  • Medical imaging (visualizing bones and cancers)
  • Treatment of cancer
• What is meant by aerial?

  An antenna, the device that transmits or receives radio waves