Electromagnetic radiation term 1

• Electromagnetic radiation


  Behaves like a wave when it travels, and like a particle when it interacts with other materials
• How electromagnetic waves are created

  1. Accelerating charges produce a continuously changing electric field

  2. The changing electric field induces a continuously changing magnetic field at 90 degrees

  3. The changing electric and magnetic fields create an electromagnetic wave
• Photon


  A quantum of electromagnetic radiation that carries a set amount of energy
• Calculating wavelength, frequency and energy of electromagnetic waves


  • Wavelength of UV wave with frequency 1.6 x 10^16 Hz = 1.88 x 10^-8 m

  Frequency of radio wave with wavelength 300 m = 1 x 10^6 Hz

  Energy of microwave with frequency 4.5 x 10^10 Hz = 2.98 x 10^-43 J

  Energy of gamma ray with wavelength 4 x 10^-14 m = 4.42 x 10^-12 J
• The higher the energy of a photon, the greater its penetrating ability
• Electromagnetic spectrum


  • Radio waves
  • Microwaves
  • Infrared radiation (IR)
  • Visible light
  • Ultraviolet light (UV)
  • X-rays
  • Gamma rays
• Electromagnetic spectrum


  • Increasing frequency, increasing energy, decreasing wavelength
• Advantages of different types of electromagnetic radiation

  • Radio and TV broadcasts; radio telescopes

  Telephone and cell phone connections; communication satellites; microwave ovens; radar systems

  Remote controls; optical fibers

  Objects reflect, refract or transmit visible light; photosynthesis

  Light bulbs; sterilization

  1. rays; CT scans; security scans

  Radiation of cancer
• Electromagnetic waves do not need a medium to propagate, they can travel through a vacuum
• Electromagnetic waves travel at the speed of light (3 x 10^8 m/s)