Physics 1.4/1.5

Physics 1.4/1.5

1. Waves

   • Red shift
     • Shows galaxies are moving away
     • Radiation from stars in distant galaxies have longer wavelengths than those in our own
   • Expanding universe
     • CMBR
     • Big bang
   • Doppler effect
     • The faster something moves the bigger the change in wavelength and frequency
     • Coming towards us it is high pitch going away it is lower
     • Source of wave is moving so waves infront get squashed their frequency increasing and wavelength decreasing
     • Waves behing the source are stretched so the opposite happens
   • Sound
     • Echoes - sound waves reflected off surfaces
     • Longlitudinal
   • Reflection in mirrors
     • Don't cross interface bounce of interface between two materials
   • Refraction
     • Wave crosses an interface between two materials and changes direction
   • Diffraction
     • Waves pass through small gap or obstacle they spread out
   • Electromagnetic waves
     • Gamma and X-rays can cause cancer
     • Visual can damage eyes
     • Infrared can cause burning
     • UV causes sunburn and skin cancer
     • Microwaves- mobile phones and satellite TV
     • Infrared- remote controls
     • Visible - photography
   • Transverse
   • Longitudinal
     • Compression
     • Rarefraction

2. Generating electricity

   • Power stations
     • Fossil fuels
       • Non-renewable
       • Coal, oil, natural gas
     • Nuclear fission
       • Non - renewable
       • Atoms split
       • Expensive to decommission
       • Takes up less room than a wind farm ect
     • Biofuels
       • Renewable
       • Wood, straw, ethanol, oil palm, gas from rotting waste
       • Uses land needed for crops
       • Not contributing to global warming as much as plants took in same amount of carbon dioxide when growing
   • Renewable
     • Wind
     • Waves
     • Hydroelectricity
     • Tides
     • Geothermal
     • Solar
   • Environment and energy
     • Pollutents in atmosphere
     • Noise
     • Visual pollution
     • Ash needs to be disposed of
     • Habitats dystroyed
   • National grid
     • Step up transformer
       • Increase voltage (decrease current)
         • Less energy wasted as current heats wires higher voltage so travels quicker
     • Step down transformer
       • Decrease voltage (increase current)
         • Voltage is safe to use
     • Mains electircity
       • Overhead
         • Easy to acces
         • Damaged by weather
         • Visual polution
         • Cause injury
       • Underground
         • Out of sight
         • Hard to access
         • Less likely to be damaged
         • More expensive