Waves

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  • Created by: Ellie
  • Created on: 02-06-13 15:54
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  • Waves
    • The basics
      • amplitude
        • height of wave
      • wavelength
        • distance from 1 peak to next
      • frequency
        • no. of complete waves per second
      • period
        • time for 1 complete wave
      • speed = frequency x wavelength
      • transverse
        • light & EM waves
      • longitudinal
        • sound & ultrasound
        • compressions
    • Electromagnetic spectrum
      • Radio
        • longest wavelength
        • lowest frequency
        • communications
      • Microwaves
        • ovens
        • satellite communications
        • heat human body tissues
      • Infrared radiation
        • night vision
        • skin burns
      • Visible light
        • photography
        • optical fibres
      • Ultraviolet
        • fluorescent lamps
        • blindness
      • X-rays
        • see inside things
      • Gamma rays
        • sterilising
        • cancer
    • Reflection refraction and diffraction
      • Diffraction
        • gap wider than wavelength
          • little diffraction
        • gap slightly wider than wavelength
          • diffraction at edges
        • gap the same as wavelength
          • maximum diffraction
      • Relection
        • angle of incidence = angle of reflection
        • mirror
          • object -> mirror = incident ray
          • eye -> mirror = reflected ray
          • object in mirror = virtual
      • Refraction
        • EM waves are slower in denser material
        • When light gos into a denser medium it bends towards the normal
        • Triangular prisms disperse white light
          • ROYGBIV
        • Refractive index
          • Glass = 1.5
          • Water = 1.3
          • = sin(i)/sin(r)
        • critical angle
          • =1/refractive index
          • angle of incidence is < critical angle
            • most of the light passes out
          • angle of incidence is > critical angle
            • it reaches total internal reflection
          • angle of incidence = critical angle
            • the emerging ray comes along the surface
    • Analogue and digital
      • analogue
        • can take any value
        • amplifying amplifies noise
      • digital
        • can only take 2 values
        • multiplexing is when multiple digital signals are sent
      • quantisation is the process of rounding values
    • Sound
      • humans hear between 20 and 20000 HZ
      • the denser the medium the faster it travels
      • Oscilloscopes
        • Turns sound waves into electrical signs,s
        • The higher the peaks the louder it is
        • The more peaks the higher the pitch

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