PHYSICS

PHYSICS

1. P1

   • The Solar System
     • Asteroids and comets are made of things left over from the formation of the solar system.
     • Comets are balls of rock dust and ice which orbit the sun
     • Asteroids are smallish lumps of rubble and rock
   • Beyond the solar system
     • Universe: 14,000 million years old
     • Sun: 5000 million years old
     • Earth: 5000 million years old
     • Speed of light: 300,000km/s
     • 1 light year is 9,460,000,000,000km
   • Looking into Space
     • Radiation can tell us a lot about stars and galaxies
     • Angle of paralax
     • Measure brightness to find distance of stars
     • Sun 150 million km away from Earth
     • sun 4.2 light years away
     • Takes light 8 seconds to get to Earth
   • The Life of the Universe
     • Universe is expanding
     • Big bang gave galaxies the force to move away
     • Greater the redshift, faster it is moving away
     • Red shift is the wavelength of light given off by a galaxy as it moves away
   • The Changing Earth
     • Rocks provide a record for changes in the Earth
     • Rocks are constantly recycled
   • Seismic Waves
     • Earthquakes cause different kinds of seismic waves
     • P-Waves
       • Travel through solids and liquids
       • Faster than S-Waves
       • Longitudinal
       • eg. sound and ultrasound
       • Vibrations in the direction that the wave is travelling
     • S-Waves
       • Only travel through solids
       • Transverse
       • Vibrations at 90* to direction of trave
     • Change speed through different materials
     • Speed=frequency x wavelength

2. P2

   • Electromagnetic Radiation
     • 1. Radio waves 2. Micro Waves 3. Infra Red 4. Visible Light 5.Ultraviolet 6. X-Rays 7. Gamma Rays
     • Energy transferred in packets called photons.
     • Gamma photons have the most energy and the highest frequency
     • Emitted from a source
     • Transmitted, reflected or absorbed
     • Intensity decreases as distance increases
   • Analogue and Digital Signals
     • Analogue signals vary
     • Digital is either on or off
     • Digital signals are easier to clean up after being amplified
     • Digital easier to process with computers
     • Digital can transmit several signals at once
   • The carbon cycle
     • Being upset
     • More CO2 released- planes, cars etc
     • Growing population- space made by chopping down trees
   • EM Radiation and the Atmosphere
     • Lots of infra red energy is absorbed by gases in the atmosphere
     • Some radiation from the sun passes through the Earths atmosphere
     • Ozone protects us from too much UV
     • Greenhouse effect helps regulate temperature
     • Earth absorbs EM radiation from the sun and warms the Earths surface up
     • Light and radio waves pass through most easily
     • Ozone=O3
   • Uses of EM Radiation
     • Non-ionising radiation doesn't have enough energy to charge atoms so it transfers energy and heats
     • Microwaves make particles vibrate,heating them up
     • Microwaves are strongly absorbed by water molecules so heat very quickly
   • Ionisation
     • Some EM radiation causes this
     • High energy EM radiation is more harmful
     • Dangerous if its in your cells
     • When a photon loses an electron
     • Can kill cells
     • Increased exposure=more damage
     • Cells divide over and over

3. P3

   • Electrical Energy
     • Power is the rate of energy transfer
     • Energy transferred=power x time
     • Power=Voltage x Current
     • Efficiency=energy usefully transferred/total energy supplied
   • Sankey Diagrams
     • Energyy is always conserved even if it's wasted
     • Thickness of arrow represents amount
   • Saving Energy
     • Home
       • Hot water tank jacket
         • Double glazing
           • Energy saving bulbs
             • draught proofing
               • loft insulation
           • Turn unused appliances off
     • Public transport/car share/cycling/walking
       • Recycling
   • Energy Sources and Power Stations
     • non renewable fuels
       • Fossil fuels; coal, oil, natural gas
       • Nuclear fuels (uranium, plutonium)
     • Renewable fuels
       • wind
         • waves
           • Tides
             • Hydroelectric
               • Solar
           • Biofuels
             • Geothermal
   • Nuclear Energy
     • Release energy by splitting atoms
     • Heat evaporates water, steam drives turbine, generator converts kinetic energy into electricity
   • Biofuels, Geothermal and Hydroelectricity
     • Biofuels are made from plant waste
     • Geothermal energy is heat from underground
     • Hydroelectricity uses dams to catch the rain
       • Requires flooding a valley
   • Generators and the National Grid
     • Moving a magnet in a wire coil induces a voltage
       • As you move the magnet through the coil the magnetic field in the coil changes and and induces a voltage and a current if the circuit is complete
     • Energy is distributed via the national grid
       • Distributed at a high voltage
         • High current loses too much heat
   • Comparison of energy resources
     • Coal
       • 36% effiicient
       • 8000 million units produced/year
       • 920g CO2 per Unit
       • Site life- 50 years
       • Cost of energy-2.4-4.5p
     • Gas
       • 50% efficient
       • 5000 million units produced/year
       • 440g-CO2 per unit
       • Site life- 30 years
       • Cost of energy- 2-3p
     • Nuclear
       • 38% efficient
       • 7000 million units produced per year
       • 110g- CO2 per unit
       • Site life 25 years
       • Cost per unit- 4-7p
     • Wind
       • 35% efficient
       • 150 million units produced/year
       • 0g -CO2 per unit
       • Site life 25 years
       • Cost per unit- 3-4p