Telecommunications

Telecommunications

1. WAVE PROPERTIES

   • Waves transfer enegry
   • d=vt
     • distance (metres) = velocity (m/s) x time (seconds)
   • v=f
     • velocity (m/s) = frequency (Hz) x wavelength ( )
       • velocity is speed
   • waves do not cause a net transfer of their medium
   • period=the time it takes for one wavelength to be produced (symbol T, measure in seconds)
     • T=1/f
       • period (seconds) = 1 / frequency (Hz)

2. LONGITUDINAL AND TRANSVERSE WAVES

   • longitudinal waves-when the vibration of the medium is in the same direction as the wave energy
     • sound waves are longitudinal
   • transverse waves-when the vibration of the medium is perpendicular to the direction of the wave engergy
     • ripples on water and light waves are transverse
   • electromagnetic waves
     • Spectrum = Radio, Microwave, Infrared, Visible, Ultraviolet, X-rays, Gamma rays
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     • electromagnetic waves can travel through a vacuum
     • electromagnetic waves travel at the speed of light 3x10 m/s through air

3. DIFFRACTION

   • diffraction is the bending of waves around obstacles or barriors
   • if a wave front is partially obstructed by a barrier then only some of the wave is able to get past it
     • the wave has a peak higher than the water to the side of it and some of the waves move into that area
       • a trough will bend around the obstacle in a similar way
   • see diffraction diagram sheet (for physical representations)

4. REFLECTION

   • see reflection sheet (for explanations and physical diagrams and representations)