PHYSICS

PHYSICS

1. ENERGY TRANSFER

   • Conduction occurs in all 3 states
     • melting/evapouration/ condensation are 3 changes of state
       • evapouration = particles gain energy, rise, become less dense and break free and evapourate into gasses
     • vacuums and insulators prevent conduction
   • Convection occurs in liquids and gasses
     • vacuums and silver surfaces prevent conduction
   • Radiation doesn't need particles to pass through
     • silvered surfaces prevent radiation
   • ENERGY TRANSFER: Energy (joules) = Power (watts) x Time(seconds)

2. GENERATING ELECTRICITY

   • NON-RENEWABLE: nuclear, coal, oil and gas.
   • RENEWABLE: wind, tidal and wave, hydroelectric, boifuels and geothermal
   • NATIONAL GRID: power station -> step up transformer -> power lines -> step down transformer, houses
   • carbon capture = storing CO2 in natural containers (sea) to reduce global warming

3. ELECTROMAGNETIC SPECTRUM

   • Transverse = oscillations areperpendicular to direction of energy transfer
     • longitudinal = oscillations are parallel
   • wave equation: V = F x
   • waves can be reflected, refracted and diffracted
     • REFLECTION
       • incident ray = reflected ray
   • humans can hear 20hz - 20,000hz
     • the higher the frequency of a wave, the higher the pitch
   • RED SHIFT/DOPPLER EFFECT
     • red shift = when a light source moves away, the wavelength increases + frequency decreases so red tint is shown
     • doppler = when a sound source moves away or closer the frequency increases or decreases meaning a higher or lower pitch
   • gamma and x-rays can travel through solids and are dangerous if exposed for long periods of time

4. ENERGY EFFICIENCY

   • Efficiency = useful energy out/total energy in X 100
   • energy CANNOT be destroyed only transferred
   • pay back time = total cost/yearly saving gives you the answer in years
   • total cost = No. of kilowatt hours x cost per kilowatt hour