AQA Physics Unit 1 (P1)

Energy transfer by heating
Best conductor: particles are close together
Best insulator: particles have larger spaces between them (conduct slower)
Evaporation: high temperature, low density, large surface area, airflow over liquid is great
Condensation: low temperature of gas, high densitiy, airflow is less
Heating and insulating buildings
U - values = how effective a material is as an insulator (conducts slower) - how fast 
Lower u-value, the better the material is an an insulator
Specific heat capacity = amount of energy needed to change the temperature of 1kg of a substance by 1 degree 
Energy efficiency at home
Most cost effective: tends to be the cheapest
(shortest pay back time - money saved covers the amount paid quickly)  
*Vaccum flask
double walled with vaccum - stops conduction, convection
silver - reduce radiation
insulating foam - minimises conduction
plastic stopper - reduce conduction  

Energy transfers and efficiency 

CONSERVATION OF ENERGY: ENERGY CANNOT BE CREATED NOR DESTROYED, only transferred, stored or dissipated 

Drawing a sankey diagram - the thickness of the arrow represents the amount of energy
(In an exam, you're normally asked to calculate the efficiency or fill in one arrow) 

Efficiency = useful/total x100 (to get %) 

Transferring electrical energy

the energy of an electrical appliance depends on:
- the power
- how long its on for 

Cost of mains electricity 

- no. of units (kwH) used = power (kW) x time (hours) 
THEN... 
- cost = no. of units x pricer per unit 

Generating electricity
- energy sources:
  >fossil fuels (coal, oil gas) uranium and plutonium (nuclear fission) biofuels
  (all used to heat water to drive a turbine) 

- types of renewable sources:
  wind, hydroelectric, geothermal, solar, wave, tidal barrages,food, biofuels

- burning non-renewable sources like nuclear fuels: 
  >release substances, waste materials produced, noise/visual pollution, destruction of         habitat 

- carbon capture: prevents carbon dioxide releasing into the atmosphere, catches it in           power stations and stores it e.g. oil or gas fields (under north sea) 

General properties of waves
Transverse: oscillations are perpendicular to the direction of energy transfer
e.g Electromagnetic waves (+mechanical)
Longitudinal: oscillations are parallel to the direction of energy transfer
e.g. Sound waves (+mechanical)
Radio - TV, Radio
Microwaves - phones, satellite tv
Infrared - remote controls
Visible - photography 

Reflection - plane mirror images = virtual, upright, laterally inverted 

Red shift
Red shift: further distant galaxy is, faster they are moving, increase in wavelength 
CMBR - low frequency waves
proves the big bang... after the big bang, it was extremely hot, high frequency radiation, as it exanded, universe cooled, microwave radiation has a low frequency now.