Physics

• Renewable energy sources


  • Hydroelectricity
  • Tidal
  • Geothermal
  • Wind
  • Nuclear
  • Solar
  • Biofuels
  • Wave
• How hydroelectricity works


  1. Converts kinetic energy into electrical energy

  2. Water flows through turbine

  3. Drives generator to produce electricity
• Hydroelectricity


  • Renewable
  • Cheap to operate
  • Expensive to construct
  • Lack of suitable locations
• Tidal electricity


  • Renewable
  • Powered by natural rise and fall of tides
  • Clean
  • Expensive
• Geothermal energy


  • Renewable
  • Takes water from underground to drive turbines
  • Can't be harnessed everywhere
  • Expensive
• Wind energy


  • Renewable
  • Doesn't release carbon dioxide
  • Doesn't need much money
  • Can affect wildlife
• Nuclear energy


  • Doesn't produce greenhouse emissions
  • Expensive
  • Potential for nuclear accidents
• Solar energy


  • Renewable
  • Converts energy from the sun into electricity
  • Works best near the equator
  • Expensive to make
• Biofuels


  • Renewable
  • Less carbon emissions than fossil fuels
  • Labour intensive
• Wave energy


  • Renewable
  • Reliable
  • No emissions
  • High cost
  • Environmental effects
• Work


  The process of transferring energy
• Power


  The rate at which work is done
• Work = Force x Distance
• Power = Work done / Time taken
• Efficiency = Useful energy output / Total energy input
• Sound travels well in solids
• Waves


  A means of transferring energy in a repeating cycle, where particles vibrate or oscillate
• Types of waves


  • Transverse
  • Longitudinal
• Transverse wave


  Vibrations occur at right angles to the direction of energy transfer
• Longitudinal wave


  Vibrations occur in the same direction as the direction of energy transfer
• Electromagnetic spectrum


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


  A measure of how many waves pass a particular point
• Frequency and wavelength are inversely proportional
• Superposition


  What happens when two waves meet after approaching each other, can result in interference
• Increasing loudness


  Increases amplitude
• Increasing pitch


  Increases frequency, decreases wavelength
• Amplitude is linked to loudness, wavelength and frequency are linked to pitch
• Musical instruments


  Produce unique tones due to the way the sound wave is made
• Ways to increase pitch on instruments


  • Flute - open/close holes
  • Violin - bow the string
  • Drum - tighten tension
• Parts of the ear


  • Outer ear
  • Ear canal
  • Eardrum
  • Ear bones
  • Cochlea
  • Auditory nerve
• How the ear works


  1. Sound waves enter ear canal

  2. Vibrate eardrum

  3. Transmitted through ear bones

  4. Into cochlea

  5. Converted to nerve signals

  6. Sent to brain
• Human hearing range


  20Hz to 20,000Hz
• Hearing range may deteriorate with age or damage from loud sounds
• Typical sound pressure levels


  • 30dB - Quiet room
  • 60dB - Normal conversation
  • 90dB - Lawnmower
  • 110dB - Rock concert
  • 140dB - Gunshot
• Decibels (dB)


  Measure of loudness of sound
• Louder sounds and longer exposure increase risk of hearing damage
• Soundproofing


  • Dense foam absorbs sound
  • Double glazing with vacuum reduces sound transmission
• Thermal conduction


  Transfer of thermal energy through direct contact between particles
• Thermal equilibrium


  When two objects have the same temperature
• Heat


  A type of thermal energy that can be transferred from one place to another