Phys - EM Spectrum

• What happens to the frequency when the wavelength changes in electromagnetic waves?


  The frequency stays the same.
• What must change when the wavelength of electromagnetic waves changes?


  The velocity must change.
• What are the main groups of the electromagnetic spectrum in order of decreasing wavelength and increasing frequency?


  • Radio waves
  • Microwaves
  • Infrared radiation
  • Visible light
  • Ultraviolet light
  • X-rays
  • Gamma radiation
• What are the colors of the visible spectrum?


  • Red
  • Orange
  • Yellow
  • Green
  • Blue
  • Indigo
  • Violet
• What is the speed of electromagnetic waves in a vacuum?


  They travel at the same high speed.
• How do electromagnetic waves behave in air compared to a vacuum?


  They travel at approximately the same speed.
• What are radio waves used for?


  Radio and television communications.
• Why can radio waves penetrate the ionosphere?


  Because they have a long wavelength.
• What are microwaves used for?


  Satellite transmissions and cooking.
• Why are microwaves more penetrating than radio waves?


  They have a greater frequency (shorter wavelength).
• What is infrared radiation used for?


  Heaters and night vision equipment.
• What is visible light used for?


  Fibre optics and photography.
• What is ultraviolet light used for?


  Fluorescent lamps.
• What are X-rays used for?


  Medical imaging and security.
• Why can X-rays penetrate materials easily?


  Because they have a very short wavelength and high frequency.
• What is gamma radiation used for?


  Sterilising food and medical equipment.
• What can microwaves cause in body tissues?


  Internal heating.
• What can infrared radiation cause?


  Skin burns.
• What risk does ultraviolet light exposure increase?


  The risk of skin cancer and blindness.
• What can prevent over-exposure to ultraviolet light?


  Sun cream and sunglasses.
• What type of radiation are X-rays and gamma rays classified as?


  Ionising radiation.
• What can ionising radiation cause?


  Mutations leading to cancer.
• How should exposure to X-rays and gamma rays be managed?


  It should be minimised using protective shielding made of very dense materials such as lead.