The Electromagnetic Spectrum

• The Electromagnetic Spectrum


  • Radio waves
  • Infrared
  • Visible light
  • Ultraviolet
  • X-rays
  • Gamma rays
• Electromagnetic waves


  • Travel at the speed of light (3x10^8 m/s)
  • Higher frequencies have smaller wavelengths and vice versa
• Higher frequencies


  Have more energy
• Radio waves


  • Emitted by astronomical objects
  • Transmitted by radio station transmitters
  • Used for transmission of information
  • Detected by antennas
• Microwaves


  • Emitted by microwave ovens
  • Used in radar stations and mobile phones
  • Used for communications
  • Detected by aerials and cell phones
• Infrared


  • Emitted by the sun and stars
  • Used in thermal cameras and medicine
  • Detected by infrared cameras, photodiodes, and skin
• Infrared radiation is invisible to the naked eye and is also called heat radiation
• Visible light


  • Emitted by the sun and other astronomical objects
  • Used in lasers and light bulbs
  • Detected by cameras and human eyes
• Ultraviolet


  • Emitted by the sun, tanning booths, and black light bulbs
  • Used for counterfeit detection and fluorescence
  • Detected by UV cameras and flying insects
• Ultraviolet is invisible to the naked eye and can be used to treat some skin conditions, but exposure can lead to skin cancer
• 1. X - rays

  • Emitted by X-ray machines and radioactive minerals
  • Used in medicine, airport security, and industry
  • Detected by X-ray film and space-based X-ray detectors
• 1. X - rays are dangerous and can damage living cells, so precautions are taken to protect people
• Gamma rays


  • Emitted by radioactive materials, exploding nuclear weapons, and gamma ray bursts
  • Used as tracers in medicine and industry, and for cancer treatment
  • Detected by gamma detectors and astronomical satellites
• Gamma radiation is very strong and can kill living cells or change their nature, and can pass through most materials
• Tracer


  A radioactive substance that is injected into or swallowed by the body, and can be detected outside the body to examine an organ or part of the body
• Tracers in medicine


  • Used to examine organs or parts of the body
  • Concentrated on the area of interest and detected outside the body
• Tracers in industry


  • Used to detect leaks in pipes
  • Sent into the water supply and detected by a detector to find the location of the leak
• Thermogram


  Shows different temperatures of a patient's body
• Infrared in medicine

  • A thermogram shows different temperatures of a patients body Warmer than healthy tissue
  • Can show up on thermograms
• Infrared cameras


  Used to detect people who may be trapped in accidents