P1 A and P1 B AQA Physics GCSE Notes

A full  set of notes that I used to revise Physics Unit 1 with last year

Preview of P1 A and P1 B AQA Physics GCSE Notes

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P1
P1A: Energy and Energy Resources
P1a 1 Heat Transfer
Conduction
-All metals are good conductors of heat/electricity: they have lots of free electrons which transfer
energy from hotter side of the metal to the cooler part
-Atoms vibrate and the vibration passes along to other atoms as they bump into each other
-Fibreglass/wool is a good insulator because it contains pockets of trapped air
Convection
- From higher temperatures to lower temperatures, through movement of fluid itself
-Convection currents-currents of hot air caused because fluids rise when heated (become less
dense)
-Examples: Hot water tank-hot water from boiler rises and flows into tank at the top, replacing
cooler water which sinks
: Sea breezes-ground heats up faster than sea so the air rises. Cooler air from the sea
takes its place and so a current occurs.
Thermal Radiation
-Flow of heat through E-M waves
-All surfaces emit radiation, and the hotter a surface the more radiation it emits
-The amount of thermal radiation radiated by something depends on:
- Its size-small objects lose heat easier than large ones as they have a larger s-a: v ratio
-Its shape
-Surface type-Dark, matt surfaces absorb and emit radiation better than light shiny ones
-Matt surfaces absorb radiation better because cavities trap and absorb heat radiation
-Material made from-glass reduces radiation emitted
Examples: Greenhouse- short wavelengths from Sun enter the greenhouse but longer wavelengths
from plants are trapped in the greenhouse by glass and so the greenhouse warms up
Heat transfer by design
Cooling by design
The cooling system of a car transfer heat from the engine to a radiator. The radiator is flat and so has
a large surface area which increases heat loss by convection in the air and through radiation. Most
cars also have a cooling fan that switches on when the engine becomes too hot. This increases the
flow of air over the radiator surface.
The Vacuum flask

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Saving Energy
Part of Loss mechanism % Method to reduce loss
house loss
Ceiling/Roof Conduction: tiles/ceiling 30 Loft insulation-reduces
Convection: Warm air rises to convection currents
ceilings/roof Conduction also reduced as
trapped air good insulator
Windows Conduction: glass 20 Double glazing, curtains
Floor Conduction 5 Carpets
Draughts Convection currents 20 Draught excluders
Walls Conduction :bricks 25 Cavity wall insulation
Convection: air spaces between bricks
Walls Radiation Aluminium foil between radiators
and walls reflect heat radiation
away from wall
- Inner wall in a cavity wall

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A rollercoaster gains GPE as it climbs. This is then lost when it race downwards and changes to kinetic
energy and sound
GPE KE + sound + thermal energy
As a ball bounces there is a continuous transfer of energy between GPE and KE. Each time the ball
bounces it loses some energy as sound and so bounces less and less. Air resistance means the ball
will also transfer heat energy.

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Electric kettle Thermal energy of water Thermal energy of kettle
Hairdryer Kinetic energy of air driven by fan Sound of motor
Thermal energy of air flowing past heater Thermal energy of hairdryer
Electric motor Kinetic energy of object driven by motor Thermal and sound energy of mot
Potential energy of objects lifted by motor
Personal stereo Sound Thermal energy of motor
Kinetic energy of motor
CD drive Energy stored in magnetic dots on disc Thermal and sound energy of mot
P1a:3 Electrical energy
Power
-Energy

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Wouldn't spoil landscape or affect people's High above the ground so unlikely to affect
health people
Less expensive and easier to repair
Easier to place as cables are hard to bury
P1a: 4 Generating Electricity
-Generated in power stations
-In coal or oil powered power satins, the burning fuel heats water in a boiler to produce steam, which
then drives a turbine
-Gas fired power stations use a powerful jet of hot gases and air to drive a turbine and can be
switched on very

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More energy produced per kg of uranium fuel Nuclear reactors are normally safe but an explosion
than from fossil fuel can release radioactive material over a wide area.
Damage lasts for years
2.

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Geothermal Energy Water heated by rocks Free energy Only possible where there are
(Earth) inside ground, due to Available all the time as hot rocks near surface so few
energy released by sun's energy not needed areas suitable
radioactive substances Cheap once built Expensive to build
inside the Earth No pollution produced
Biomass Rotting matter burnt to Plants are renewable Contributes to Greenhouse
(sun) produce electricity Natural waste used up effect
Set up costs low Requires a large area of land
P1B:Radiation and the Universe

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Electromagnetic Spectrum
-All transverse waves
-All travel at a speed of 300 million m/s
-Can travel through a vacuum
-The shorter the wavelength and the higher the frequency the more dangerous they are
-Some waves are reflected depending on wavelength/type of surface
-Some or all waves are absorbed by a substance.

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Radio-waves and the Ionosphere
Radio waves less than 30 MHz reflected back into the atmosphere
However ionosphere stronger in summer than in winter so cannot hear distant radio stations
Type of Radiation Uses Dangers
Radio Waves Communication
Astronomy
Microwaves Satellite communications Internal tissue heating as water
Cooking food molecules resonate causing them
RADAR to get hotter
Infra-red radiation Remote controls Skin burns
Optical fibre communications
Night vision(IF camera)
Grills/toasters
Visible light Seeing Blindness
Endoscopes
UV radiation Sun beds High doses can kill cells
Security marking/fluorescent

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Isotope is an atom which has the same number of protons and electrons but a different number of
neutrons: same atomic number but a different mass number
-Most atoms have 3 isotopes but only ½ are stable
Alpha Radiation
Poor penetrating-stopped by paper
-Heavy and large
- Highly ionising as very dangerous as affects all the surrounding tissue in the body and
absorbed by skin cells
-Helium nucleus
-Deflected by magnetic fields-positive charge
Beta Radiation
-Deflected by magnetic fields in opposite way to alpha
-

Comments

fatima

Thu 9th May, 2013 @ 13:33


THANKZ, great resources

Ankita

Wed 12th June, 2013 @ 21:01

no hepkp

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