AQA GCSE Physics Unit 1 - Key points for P1

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AQA Physics Unit 1 ­ Key Points
1.1 Infrared radiation
Infrared radiation is energy transfer by electromagnetic waves.
All objects emit infrared radiation.
The hotter an object is, the more infrared radiation it emits in a given time.
1.2 Surfaces and radiation
Dark, matt surfaces emit more infrared radiation than light, shiny surfaces.
Dark, matt surfaces absorb more infrared radiation than light, shiny surfaces.
Light, shiny surfaces reflect more infrared radiation than dark, matt surfaces.
1.3 States of matter
Flow, shape, volume and density are the properties used to describe each state of matter.
The particles in a solid are held next to each other in fixed positions.
The particles in a liquid move about at random and are in contact with each other.
The particles in a gas move about randomly and are much further apart than particles in a solid or
1.4 Conduction
Metals are the best conductors of energy.
Materials such as wool and fiberglass are the best insulators.
Conduction of energy in a metal is due mainly to free electrons transferring energy inside the
Non-metals are poor conductors because they do not contain free electrons.
1.5 Convection
Convection is the circulation of a fluid (liquid or gas) caused by heating it.
Convection takes place only in liquids and gases.
Heating a liquid or a gas makes it less dense so it rises and causes circulation.
1.6 Evaporation and condensation
Evaporation is when a liquid turns into a gas.
Condensation is when a gas turns into a liquid.
Cooling by evaporation of a liquid is due to the faster-moving molecules escaping from the liquid.
Evaporation can be increased by increasing the surface area of the liquid, by increasing the liquid's
temperature, or by creating a draught of air across the liquid's surface.
1.7 Energy transfer by design
The rate of energy transferred to or from an object depends on:
The shape, size and type of material of the object
The materials the object is in contact with
The temperature difference between the object and its surroundings.
1.8 Specific heat capacity
The greater the mass of an object, the more slowly its temperature increases when it is heated.
The rate of temperature change of a substance when it is heated depends on:
The energy supplied to it

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Its mass
Its specific heat capacity
Storage heaters use off-peak electricity to store energy in special bricks.
1.9 Heating and insulating buildings
Energy transfer from our homes can be reduced by fitting:
Loft insulation
Cavity wall insulation
Double glazing
Draught proofing
Aluminium foil behind radiators
U-values tell us how much energy per second passes through different materials.
Solar heating panels do not use fuel to heat water but they are expensive to buy and install.
2.…read more

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P= E
Efficiency = useful power out
total power in (x 100%)
3.3 Using electrical energy
The kilo-watt hour is the energy supplied to a 1 kW appliance in 1 hour.
Total cost = number of kWh used x cost per kWh
3.4 Cost effectiveness matters
Cost effectiveness means getting the best value for money.
To compare the cost effectiveness of different appliances, we need to take account of costs to buy it,
running costs and other costs such as environmental costs.…read more

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Gas-fired power stations and pumped-storage stations can meet variations in demand.
Nuclear, coal and oil power stations can meet base-load demand.
Nuclear power stations, fossil-fuel power stations using carbon capture and renewable energy are
all likely to contribute to future energy supplies.
5.1 The nature of waves
We use waves to transfer energy and transfer information.
Transverse waves vibrate at right angles to the direction of energy transfer of the waves. All
electromagnetic waves are transverse waves.…read more

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The loudness of a note increases if the amplitude of the sound waves increases.
Vibrations created in an instrument when it is played produce sound waves.
6.1 The electromagnetic spectrum
The electromagnetic spectrum (in order of decreasing wavelength, increasing frequency and
energy) is:
radio waves
infrared radiation
ultraviolet radiation
gamma radiation and x-rays
The wave speed equation is used to calculate the frequency or wavelength of electromagnetic
6.…read more

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