Uses of EM Waves

• What should you be able to describe by the end of the video?

  Uses of electromagnetic waves
• What is required of higher tiered students regarding electromagnetic waves?

  They need to explain the suitability of each type of electromagnetic wave for its uses.
• What are the uses of radio waves?

  • Transmit radio signals
  • Transmit terrestrial TV signals
• Why are radio waves suitable for transmitting signals over long distances?

  Because they can travel long distances before being absorbed.
• What phenomenon allows longer wavelength radio waves to spread out between hills?

  Diffraction allows them to spread out between hills.
• How do radio waves travel long distances around the Earth?

  By reflecting off the ionosphere.
• What are the two main uses of microwaves?

  • Heating food
  • Communicating with satellites
• Why are microwaves effective for heating food?

  Because water molecules in food absorb microwave energy, causing temperature increase.
• Why can microwaves communicate with satellites effectively?

  They can pass through the Earth's atmosphere without reflection or refraction.
• What are the uses of infrared waves?

  • Emitted by electrical heaters
  • Used to cook food in ovens
  • Used in infrared cameras
• How does infrared energy affect the temperature of objects?

  It is easily absorbed, increasing the temperature of objects.
• What is a practical application of infrared cameras?

  To check buildings for heat losses.
• What is a key use of visible light in communication?

  • Communication using fiber optics
• How do optical fibers transmit information?

  By transmitting pulses of light down thin strands of glass.
• Why can visible light carry a great deal of information?

  Because it has a short wavelength.
• What are the uses of ultraviolet light?

  • Energy-efficient lightbulbs
  • Sun tanning (e.g., tanning beds)
• Why are energy-efficient lightbulbs advantageous?

  They require much less energy than normal light bulbs.
• What is a health risk associated with ultraviolet light?

  It increases the risk of skin cancer and causes premature aging.
• What are the uses of x-rays and gamma rays?

  • Medical imaging (e.g., visualize broken bones)
  • Detect cancers
  • Medical treatments (e.g., treat cancer)
• Why are x-rays effective for visualizing broken bones?

  Because they are absorbed by bones, making them visible.
• How do x-rays and gamma rays differ in their medical applications?

  Gamma rays are used to detect cancers, while x-rays visualize broken bones.
• What is a common characteristic of both x-rays and gamma rays?

  They are very penetrative and can pass through body tissue easily.
• How are x-rays and gamma rays used in medical treatments?

  To treat conditions like cancer.