Physics- paper 1

• Types of energy


  • Kinetic
  • Gravitational potential
  • Electrical
  • Chemical
  • Thermal
  • Sound
  • Nuclear
• Conservation of energy: energy can't be created or destroyed
• Closed system


  e.g. a swing - gravitational energy converts to kinetic energy and thermal energy (due to friction)
• Energy transfer by conduction

  1. Particles vibrate a lot

  2. Cool particles vibrate a little

  3. Fast-moving particles collide with neighbouring particles

  4. This gives them more energy, making them vibrate even faster
• Insulation


  Keeps heat in and cold out
• Types of insulation


  • loft insulation
  • Double glazing
  • Cavity wall
• Specific heat capacity


  The amount of energy required to heat 1kg of the object by 1°C
• Energy resources


  • Fossil fuels
  • Electricity
  • Greenhouse gases
  • Solar power
  • Wind power
  • Tidal power
  • Nuclear power
  • Hydroelectricity
• Fossil fuels


  • Burning coal, oil, gas makes cheap and reliable electricity
  • Greenhouse gases trap heat in the atmosphere
• Solar power


  • Uses the sun's light energy to convert it to electricity
  • Cheap
  • Cuts carbon footprint
  • Only works if there's enough light
• Wind power


  • Uses kinetic energy from the wind
  • Cheap
  • Cuts carbon footprint
  • Only works if it's windy
  • Noise pollution
  • Not nice to look at
• Tidal power


  • Uses changing water levels from tides
  • Reduces carbon footprint
  • Tides only go in and out twice a day
  • Not nice to look at
• Nuclear power


  • Finite resource - will eventually run out
  • Dangerous, fatal if goes wrong
  • Doesn't need much fuel
  • Very efficient
• Hydroelectricity


  • Renewable, lots of water so won't run out
  • Destroys land to make a big dam
  • Not carbon neutral
  • Once built, won't run out
  • Not very dangerous
• Potential difference


  Measure of how much energy is transferred between 2 points in a circuit
• Current


  Flow of electrons through a conductor
• Resistance


  Opposition to the flow of charge
• Circuit components


  • Cell
  • Bulb
  • Ammeter (measures current)
  • Voltmeter (measures voltage)
  • Negative forces
  • Resistor
  • Variable resistor (changes resistance)
  • Switch (open/closed)
  • Thermistor
  • Buzzer
  • Motor
• Series circuit


  Current only has one path, current is always the same, voltage splits up
• Parallel circuit


  Current has multiple paths, current splits up, voltage is always the same
• Mains electricity comes out at 230V and 50Hz
• Transformer


  Steps up voltage to travel far, steps down voltage to be safe
• Fuse


  Breaks to stop excess current, preventing fire
• Power


  Energy transferred per second
• Kilowatt hours


  How electricity companies charge for electricity usage
• Solid


  • Fixed position, vibrate in a pattern
• Liquid


  • Not fixed position, vibrate fast with no pattern
• Gas


  • No fixed position, vibrate randomly with high kinetic energy
• Increasing pressure


  Increases temperature, volume decreases, number of particles increases
• Rutherford's gold foil experiment showed most of the atom is empty space, with a dense nucleus
• Types of radioactive decay

  • Alpha
  • Beta
  • Gamma
• Alpha radiation


  • Most ionising, stopped by paper
• Beta radiation


  • Moderately ionising, stopped by aluminium
• Gamma radiation


  • Least ionising, stopped by thick lead
• Half-life


  Time for the number of radioactive nuclei to halve
• Nuclear fission


  Large nucleus splits into 2 smaller nuclei, releasing energy
• Nuclear fusion


  2 small nuclei combine to form 1 larger nucleus, releasing energy