P1

P1

1. Heat

   • Conduction and Convection
     • CONDUCTION occurs mainly in solids
       • CONDUCTION OF HEAT is the process where vibrating particles pass on extra kinetic energy to neighbouring particles
     • CONVECTION occurs in liquids and gasses
       • CONVECTION occurs when more energetic particles move from the hotter region to the cooler region- and take their heat energy with them
         • CONVECTION CURRENT
   • Heat Radiation
     • RADIATION is how we get heat from the sun
     • All objects emit and absorb Heat Radiation
     • RADIATION is important in cooking
       • Grils and Toaters heat food using INFARED (heat) radiation, increasing the surface particles kinetic engery. The energy is then CONDUCTED/ CONVECTED into the food.
       • Microwave Ovens use radiation to cook food- microwaves are electromagnetic waves that have a different wave lengh to infared.
         • Microwaves penetrate 1cm into the outer layer of food, where they are absorbed by water or fat molecules, increasing their kinetic energy. The energy is then CONDUCTED /CONVECTED into the food.
   • Moving and Storing Heat
     • HEAT is a measure of energy
     • TEMPERATURE is a measure of heat.
     • Energy (J) = Mass x Specific Heat Capacity x Temperature Change
       • Energy ------------------------- Mass x SHC x Temp Ch
     • SPECIFIC HEAT CAPACITY tells you how much energy stuff can store
   • Melting and Boiling
     • Energy is needed to break Intermolecular Bonds
     • SPECIFIC LATENT HEAT is the energy needed to change state
     • Energy = Mass x Specific Latent Heat
       • Energy ------------------ Mass x SLH

2. Energy

   • Saving Energy
     • INSULATING your house saves energy and money
       • Payback Time = initial cost of investment / saving per year
         • ICI --------- PT x S/Y
       • For Example Loft insulation, Thick Curtains, Double Glazing etc.
     • THERMOGRAMS show where your house is leaking heat
       • A THERMOGRAM is a picture taken with a thermal imaging camera. Objects at different temperatures emit infared rays of different wave lenghs. The THERMOGRAM displays the differnt temperatures in different colours
         • White, Yellow and Red show hot areas
         • Black, Dark Blue and purple show cold areas
         • If a house looks 'hot' it is looking heat to the outside.
   • Efficiency
     • All machines waste some energy
     • More efficient machines waste less energy
     • Efficiency(%) = ( useful energy output / total energy input ) x 100
       • UEO ---------------x100 E x TEI
   • Sankey Diagrams
     • The thickness of the arrow represens the amount of energy
     • Shows energy transformation

3. Waves

   • Basics
     • • a = amplitude
         • The displacement from rest position to the crest/trough
       • Wavelengh
         • The lengh of the full cycle of the wave (eg from crest to crest)
       • rest position
         • the line
       • crest/peak
         • the very top of the wave
       • trough
         • the very bottom of a wave
     • Frequency
       • The number of complete cycles or oscillations passing a certain point per second (measured in Hz)
       • frequency (Hz) = 1 / Time
         • 1 --------- f x t
     • wave speed = frequency x wavelengh
       • V ------- f x λ
   • Wave Properties
     • Waves can be relfected, refracted and difracted
       • Reflection of light lets us see things
       • Diffraction= the bending (spreading out)of waves when they pass through a gap, past an edge or around a corner. Diffraction is a general property of all waves caused by interference
       • Refraction= when a wave meets a boundry at an angle which causes it to changes direction.
     • Angle of incidence = Angle of Reflection
     • Total internal Reflection depends on the Critical Angle
       • Total Internal Reflection(TIR)= when a wave is expected to refract, but actually reflects back
       • Critical Angle= the angle above which Total internal Reflection occurs
   • EM Waves and Communication
     • There are seven types of ELECTROMAGNETIC (EM) Waves.
     • The properties of EM Waves depend on FREQUENCY and WAVELENGH
     • Different sorts of signals have different advantages.
       • eg. radio, cooking, mobile phones etc.

Imagens e arquivos do mapa