Zusammenfassung der Ressource
Physics P1 Revision
- Energy
- Heat
- Can be transferred by
conduction, convection,
or radiation
- Infrared radiation
- Electromagnetic waves
- Dark matt surfaces absorb and emit information best
- Shiny silver surfaces best reflect heat
- All objects absorb
and emit radiation
- Rate of heat transfer
depends on surface
area
- Specific heat capacity
- Energy (E in Joules)= Mass (M in kg) x Specific Heat
Capacity (J/kgC) x Temperature change (theta)
- Types of energy
- Electrical
Light Sound
Kinetic
Nuclear
Thermal
Gravitational
Elastic
Chemical
- The last three
are forms of
stored energy
- Conduction, Convection and Radiation
- Conduction
- Kinetic theory explains the 3 states of matter (solid, liquid, gas)
- Solid- strong forces of attraction,
not much energy so can only vibrate
around fixed positions
- Liquid- weaker forces of attraction,
mcan form irregular arrangements,
more energy so can move in random
directions at low speeds
- Gases-No attraction between the particles, and the
most energy, and are free to move at high speeds
- Mainly in solids.
- Extra kinetic energy turns into heat
- Best in metals because of free electrons
- Convection
- Liquids and gases only
- Circle of heating, travelling then cooling
- Heat radiation infrared energy
- Bigger surface area, more infrared waves can be emmitted
- Energy Transfer
- Condensation and evaporation
- When a gas cools and lose kinetic energy
- If it gets close enough the gas becomes a liquid
- Vice versa for evaporation
- The rate of evaporation is best due to high temperatures,
low density, larger surface area, and high airflow
- Electricity
- Cost of Electricity
- Energy= Power x time
- kWh=Kilowatt-hours
- Total energy from two metre
readings= subtract the smaller
from the end
- Electrical Appliances
- Which one is more cost
effective or uses less energy
- Standard of living is affected by access to electricity
- Energy and the Environment
- Renewable energy
- Wind power- turbines create no pollution, very
noisy, rely on wind, high initial cost but no
running costs and no permanent damage
- Solar Cells- No pollution, but some to create them,
very reliable during the day in sunny countries, high
initial costs, Expensive to connect to the national grid
- Hydroelectric is is used in dams and falling water- expensive and difficult to
build, reliable, cheap to connect to the national grid, loss of habitats
- Pumped storage is used to save energy
- Geothermal and biofuel use heat
- Non renewable energy
- Creates CO2 through combustion, sulphur
dioxide causing acid rain, nuclear waste is
dangerous
- Comparisons
- Initial costs, reliability
issues, environmental
issues, set
up/decommissioning
time, running costs,
location issues
- National Grid
- Current creates heat so a step
up/step down increases voltage to
decrease current and vice versa
- How electricity is transferred
- Waves
- Basics
- Waves have amplitude- height from the middle, wavelength,
which is from crest to crest, or frequency in Hz
- Transverse waves have sideways vibrations
- Longitudinal waves are along the same lines
- Wave Speed (m/s)= Frequency (Hz) x Wavelength (m)
- Refraction + Diffraction
- Diffraction - waves spreading out.
- When a gap is the same size as wavelength= maximum diffraction
- Refraction- changing speed changes direction
- Crossing a boundary between 2 substances EG glass to air
- Electromagnetic Spectrum
- Radiowaves
Microwaves
Infrared
Visible Light
X-ray
Gamma
Rays
- Radiowaves are used for communication
- Microwaves are used for satellite communication and mobile phone
- Infrared used for remotecontrols
- Origin of the universe
- Red shift
- Light is shifted towards the red end of the spectrum
- Shows that everything is moving away from us
- Big Bang
- Cosmic background microwave radiation
was origionally gamma rays when the big
bang occurred
- This has been stretching out since the Big bang proving that the
universe is expanding
- Efficiency
- In the home
- Short payback time
- Cavity wall insulation-
stops convection and
radiation
- Loft insulation
stops conduction
and radiation
- Draught proofing-
Reduce convection
- Hot water tank
jacket-reduces
conduction and radiation
- Thick curtains-
Conduction and
radiation
- Efficiency= Useful Energy Out/
Total energy in
- Useful energy is
concentrated energy
- The entire energy output
of a machine end up as
heat
- Sankey Diagram- Always to scale