Science

• Wave


  A disturbance that transfers energy from one place to another in a regular and organised way
• Wave


  Particles that are sent through vibration
• Types of waves


  • x-rays
  • ultra violet (uv)
  • infra red
  • radio
• General categories of waves


  • Mechanical
  • Electromagnetic
• Two types of mechanical waves


  • Transverse
  • Compression
• Mechanical waves


  • Require a medium to travel through
  • Cause particle to oscillate
• Electromagnetic waves


  • Do not require a medium to travel through
  • Are composed of vibrations
  • Are not composed of electric and magnetic fields
• Mechanical waves cause particles to vibrate around fixed positions, particles are not transmitted
• Electromagnetic waves do not directly cause things to vibrate, they are made up of protons
• Crest

  Peak of the wave
• Wavelength

  Distance between same points on an adjacent angle
• Amplitude

  Height of wave above its resting point
• Trough

  Low point of wave
• Frequency


  Number of waves that go past in one second
• Velocity


  The times it takes for a wave to travel a known distance (where you started over the time it takes to get there)
• Oscillate

  Vibrate around a fixed point
• Period


  Time it takes for wave to form
• Units for measuring wavelength


  • Metres
  • Kilometres
• Unit for frequency


  Hertz (Hz)
• Sound wave


  • Sound is a compression wave that requires a media
  • Travel speed depends on the media
• Sound can be used for communication
• Sound travels through a denser material

  Faster
• Sound


  • Bounces
  • Causes objects to vibrate
• Sound travels about 300 ms-1 in the air
• Sound can be used for

  Navigation, surgery, measuring distance, see things
• What is the doppler effect


  The doppler effect is a change in frequency that occurs when a source and observer move relative to one another. The speed of a wave is fixed as long as its in the same media.
• The doppler effect can used for


  Measuring the speed of a wave as it travels away or closer to you (sonar/radar)
• What is EMR


  a form of energy that is generated when electrically charged particles move through matter or a vacuum.
• What is EMR composed of

  Quanta, tiny packets of energy that travel in linear beams
• EMR spectrum

  radiowaves, microwaves, infrared, visible light, ultraviolet, x-rays and gamma rays
• EMR colour spectrum

  red, orange, yellow, green, blue, indigo, violet
• Radio

  News, wifi, tv
• Microwave

  heating food, communications
• x-ray

  medical purposes
• infra red

  L.O.S, remote control, motion sensors
• Light

  Lasers, fibre optic
• UV

  Kill bacteria, mineral and crime scene inverstigations
• Gamma ray

  sterilisation, radio therapy
• When EMR goes from a low density medium into a higher density one, it slows down. If it goes from high density to low density it speeds up.
• Reflection: Light bouncing

  Refraction: Light bending