Electromagnetic 222

• Radiation


  The flux of particles or waves emitted by the body

  
• Emission


  Radiation generation - release or discharge o particles energy or radiation from a source

  
• Electromagnetic radiation (electromagnetic wave)

  A disturbance of the electromagnetic field propagating in space

  
• Electromagnetic radiation


  • Consists of electromagnetic waves, which are synchronized oscillations of electric and magnetic fields

  
• Frequency


  Determines the different wavelengths of the electromagnetic spectrum

  
• In a vacuum, electromagnetic waves travel at the speed of light

  
• Speed of light in vacuum (c)

  A universal physical constant that is exactly equal to 299,792,458 metres per second
• According to the special theory of relativity, c is the upper limit for the speed at which conventional matter or energy (and thus any signal carrying information) can travel through space
• Electromagnetic waves


  • The electric and magnetic components induce each other - a changing electric field produces a changing magnetic field, and vice versa

  
• Photon


  A massless elementary particle that carries the energy of an electromagnetic wave

  
• Planck's relation


  E = hf, where E is the energy of the photon, h is Planck's constant, and f is the frequency of the wave

  
• James Maxwell was the first to formulate the theory of electromagnetic waves
• Photon


  An elementary particle with no electric charge or magnetic moment, and a rest mass of 0
• The human eye sees only a small part of the electromagnetic radiation, with a wavelength in the range of 380-780 nm

  
• Electromagnetic wave energy


  • In a vacuum, the electrical and magnetic components of the energy carried are equal, while in a medium with non-zero electrical conductivity they are different

  
• Radiation of electromagnetic waves (according to increasing energy)

  • Radio radiation
  • Microwaves
  • Thermal radiation
  • Infrared light radiation
  • Solar radiation
  • Laser radiation
  • Ultraviolet radiation
  • X-rays
  • Synchrotron radiation
  • Gamma radiation
• EM radiation with a wavelength between approximately 400 nm and 700 nm is directly detected by the human eye and perceived as visible light

  
• As frequency increases into the visible range, photons have enough energy to change the bond structure of some individual molecules
• The change in retinal causes a change in the shape of the rhodopsin protein, which starts the biochemical process that causes the retina of the human eye to sense the light
• Waves


  • Disturbance of a field oscillating from a resting point
  • Travels through time and space, transferring energy
  • Can only exist in fields with a force returning it to equilibrium

  
• Standing waves


  Have a constant amplitude of oscillation at different points

  
• Frequency


  Number of waves passing a point per second
• Wavelength


  Distance between adjacent parts of the wave

  
• Amplitude


  Distance between resting point and the max wave displacement
• Period


  Time taken to complete a wave cycle
• Velocity


  The speed of the disturbance
• Electromagnetic waves


  • Synchronized oscillations of electric and magnetic fields
  • Propagate through space and carry electromagnetic radiant energy
  • Do not require an initial energy input or medium
  • May still travel through a medium
  • Travel at the speed of light
  • Photon is the quantum of the electromagnetic field and the force carrier for electromagnetic force

  
• Electromagnetic Spectrum


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


  Have the lowest energy level in the spectrum and carry signals to receivers that translate them into information
• Microwaves


  Have the second lowest energy level and frequency in the spectrum, can pass through rain, clouds, smoke, and more
• Infrared waves


  Can be released as heat or thermal energy, have a relatively low frequency and energy level, and a relatively long wavelength

  
• Visible light waves


  Are the only visible waves on the spectrum, different colors represent different wavelengths, light passes through matter and is absorbed or reflected depending on wavelengths

  
• Ultraviolet waves


  Begin the shorter wavelengths in the spectrum, are energetic light waves with high frequency, and are emitted by high temperature processes

  
• 1. rays


  Have a very high energy levels with short wavelengths, are produced by very high temperature sources, and are characterized by their penetrating radiation

  
• Gamma waves


  Have the highest frequency in the spectrum, have nuclear energy and the shortest wavelength, and can destroy living cells
• Ultraviolet radiation


  Electromagnetic radiation with a wavelength from 10 nm to 400 nm, invisible to humans and with energies from 3 eV to 12.4 eV

  
• Ultraviolet radiation subdivisions


  • Ultraviolet A (UVA), long wave - 400 nm to 315 nm
  • Ultraviolet B (UVB), medium wave - 315 nm to 280 nm
  • Ultraviolet C (UVC), short wave - 280 nm to 200 nm

  
• Ultraviolet radiation is classified as ionizing radiation, i.e. it has the ability to detach electrons from atoms and molecules
• The Sun emits ultraviolet over a wide spectral range, but the upper layers of the atmosphere absorb most of the harmful UVC and UVB radiation
• Ultraviolet (UV) radiation


  Electromagnetic radiation with a wavelength from 10 nm to 400 nm, invisible to humans and energies from 3 eV to 12.4 eV