Physics P1

Physics P1

1. electricity

   • Sankey diagram
     • sankey diagram of a light
   • Energy
     • payback time
       • The amount of time that it take to pay off installation costs
       • The double glazing cost £3000 and saves £150 a year = 20 years to pay back
     • can be stored, transfered or disipated
     • efficiency = (useful energy transferred / energy supplied) x 100
       • answer is in a percentage
     • Energy is given in different forms
       • light,heat,sound and electrical are the main forms

2. Transfer of energy with heat

   • conduction
     • the transfer of heat energy without the object moving
     • metals are good conductors
       • when the heat hits a metal it causes a vibration in the atoms and this creates friction and heat
       • they have the most closely packed atoms
   • convection
     • the transfer of heat energy by moving liquid or gas
       • not in a solid
       • expands when heated
     • hot gas rises and colder gas falls
       • how hot air balloons work
       • convection currents
   • radiation
     • electromagnetic energy given off a hot object
       • no atoms or particles are invloved
     • all objects give out and take in thermal radiation
       • infrared radiation
     • dark matte surfaces take in the best heat
       • shiny light coloured surfaces take in the radiation in the least
         • it reflects the heat back onto the object its been given off from
   • heat lost through homes
     • mainly lost by convection and conduction
     • reduces by draught excluders and curtains
     • double glazing and insolation are the best ways of keeping the heat in.

3. transferring electrical energy

   • E=PxT
     • E is energy transferred in kilowatt-hours, kWh
     • P is power in kilowatts, kW
     • t is time in hours, hours
   • • they increase the voltage so they don't loose as much energy as they would with a low voltage

4. generating elecricity

   • fossil fules
     • such as coal are then burnt to produce to turn water to steam this is then used to turn a turbine and connected to a generator
     • advantages
       • very quick to burn
       • easy to gather coal
     • diadvantages
       • supply is limited
       • causing global warming due to carbon dioxide
   • nuclear fuels
     • uranium and plutonium
       • radioactive metals
     • nuclear fission
       • a nuclear reaction in which a heavy nucleus splits spontaneously or on impact with another particle, with the release of energy.
     • advantaages
       • doesn't produce greenhouse gasses
       • produces a large amount of energy in one go
     • disadvantages
       • nuclear fuels are non-renewable energy resources
       • nuclear waste remains radioactive and is hazardous to health for thousands of years.
   • wind power
     • the wind turns turbines and a generator turns it into elecricity
     • advantages
       • Wind is a renewable energy resource
       • no greenhouse gasses are produced
     • disadvantages
       • Wind farms are noisy and may spoil the view
       • the amount of energy can vary if there is no wind then there is no power
   • Geothermal energy
     • hot rocks under the surface heat up water creating steam which turn turbines and create electricity
     • advantages
       • Geothermal energy is a renewable energy resource
       • no fuel costs
     • disadvantages
       • Most parts of the world do not have suitable areas
       • equipment can cost lots of money
   • Solar energy
     • Solar cells are devices that convert light energy directly into electrical energy.
     • advantages
       • Solar energy is a renewable energy resource and there are no fuel costs
       • Solar cells provide electricity in remote locations
     • disadvantages
       • Solar cells are expensive and inefficient,
       • Solar cells do not work at night.
       • cost lots of money

5. Waves

   • Waves are vibrations that transfer energy from place to place
     • doesn't need any atoms
       • Visible light, infrared rays, microwaves
       • They can travel through empty space. Electrical and magnetic fields vibrate as the waves travel.
     • Some waves must travel through a substance.
       • the medium
       • Sound waves and seismic waves
       • the medium that vibrates as the waves travel through.

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