# Physics 2

• Created by: Fiona2002
• Created on: 27-10-17 16:50
Name the eight energy stores
Thermal; kinetic; gravitational potential energy; elastic; chemical; nuclear; electromagnetic; electrostatic
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How can energy be transferred between stores?
1) HEATING: energy is transferred from a hotter region to a colder region. This happens through CONDUCTION & CONVECTION. 2) It can also be transfered by 'work done' mechanically (object has a force exerted on it) or electrically
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What is 'CONDUCTION' in heating?
Conduction is where the vibrating particles of a substance transfer energy to neighbouring particles
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What is 'CONVECTION' in heating?
Convection is where the energetic particles of a substance move away from hotter to cooler regions
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Why is transferring energy by electricity convenient?
Transferring energy by electricity is convenient because it is easy to do as it just requires a charge doing electrical work against resistance
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State the Conservation of Energy Principle
Energy can be transferred usefully, stored or dissipated, but can never be created or destroyed
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What does 'dissipated energy' mean?
Dissipated energy is also known as 'wasted energy' as the energy is stored in a way that is not useful
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The net change in total energy of a closed system is always zero - True or false
True
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What does the power rating of an electrical appliance describe?
This shows their maximum operating power so higher power rating = more energy per second
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What is the equation that links energy transferred, power and time?
Energy transferred (j) = power (w) x time (s)
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What is a kilowatt hour (kWh)?
A kilowatthour is the amount of energy a device with a power of 1kW (1000w) transfers in an hour of operation
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What is the equation for calculating the efficiency of an energy transfer?
useful energy transferred / total energy transferred
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How can you reduce unwanted energy transfers in a motor?
By lubricating it
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How can you reduce unwanted energy transfers in buildings?
Thermal insulation (thick curtains, loft insulation, double glazed windows, thick walls)
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What does a sankey diagram represent?
It shows all the energy transfers made by a device; the useful & wasted energy
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What are renewable resources and give examples
Renewable resources are resources that will never run out. For example: the sun, hydroelectricity, wind
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What is non-renewable resources and give four examples
Non-renewable resources will eventually run out one day. For example: coal, oil, gas (fossil fuels), uranium
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Give disadvantages of using fossil fuels
They damage the environment: coal, oil & gas release CO2 -> greenhouse effect -> global warming
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Explain how a power station uses fossil fuels to produce electricity
As the fossil fuel burns water is heated; water boils-> steam->turns turbine; turbine is connected to an electrical generator-> voltage +current; current produced flows to national grid
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Give two disadvantages of using solar power and wind power
1) Solar only works in places with a lot of sun+ does not work at night/ wind only works in places with a lot of wind 2) can spoil the view or be noisy
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Give two advantages of using solar power and wind power
1)no pollution; 2) no fuel costs
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Describe the benefits & drawbacks of using biofuel
+ can be made from many things (e.g. farm waste/ rubbish); renewable; can be burnt to produce electricity; fairly reliable// - high costs; large areas of land have been cleared for biofuel crops resulting in some species loosing their habitats
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Describe hydroelectricity
= building dams; water is stored and allowed out through turbines; big impact on environment due to flooding & loss of habitats; + immediate response, minimal running costs
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Describe tidal barriages
= using the sun; as tides come in it fills estuaries, the water is let out through turbines; no pollution but can alter habitats & affect boat access & spoil the view; high reliability
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How has energy usage changed in the past few years?
Energy usage has increased; this is because: the population is increasing, technologies advance, lifestyles change (e.g. jobs)
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What is the national grid?
A giant web of wires & transformers that covers UK and connects power stations to consumers- gives electricity to homes and other places
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State the freuency and potential difference of the UK mains supply
Mains supply uses A.C at around 230 VOLTS & 50 Hz
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What type of current do mains supply?
Alternating current (A.C.)
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What type of current do batteries supply?
Direct current (D.C)
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What is direct current?
A current that always flows the same direction. It's created by a direct voltage
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What is a NEUTRAL WIRE?
BLUE WIRE- electricity flows in through the live wire and out through the neutral wire. The neutral wire is always 0 volts
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What is a LIVE WIRE?
BROWN WIRE- carries the voltage, 23 volts
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What is an EARTH WIRE?
GREEN & YELLOW WIRE- for safety, carries away the current if something goes wrong. 0 volts
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## Other cards in this set

### Card 2

#### Front

How can energy be transferred between stores?

#### Back

1) HEATING: energy is transferred from a hotter region to a colder region. This happens through CONDUCTION & CONVECTION. 2) It can also be transfered by 'work done' mechanically (object has a force exerted on it) or electrically

### Card 3

#### Front

What is 'CONDUCTION' in heating?

### Card 4

#### Front

What is 'CONVECTION' in heating?

### Card 5

#### Front

Why is transferring energy by electricity convenient?