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Physics - P1 > Topic 5 - Generation & Transmission Electricity > Flashcards

Topic 5 - Generation & Transmission Electricity Flashcards

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1
Q

What is electric current?

A

Flow of charge round a curcuit

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2
Q

what carries charge

A

electrons - negatively charged particiles

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3
Q

what is voltage (potential difference)

A

an electrical pressure giving a measure of the energy transferred.

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4
Q

which way does the current flow in a circuit?

A

negative to positive

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5
Q

what does A.C stand for?

A

alternating current

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6
Q

what is an alternating current?

A

it is a current supplied by the mains electricity. the voltageis alternating as it keeps changing direction

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7
Q

what does D.C stand for?

A

Direct Current

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8
Q

What is a direct current?

A

it is supplied by batteries or solar cells. the voltage stays the same as it flows in the same direction.

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9
Q

what is electrical power?

A

energy transferred per second. it tells you how fast an appliance transfers electrical energy. the higher the power of your appliance the more energy it transferred every second

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10
Q

What is the unit for power?

A

Watts (W)

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11
Q

what is the unit for current?

A

Amps (A)

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12
Q

what is the unit for voltage?

A

Volts (V)

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13
Q

what is the symbol for power

A

P

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14
Q

What is the symbol for current

A

I

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15
Q

what is the symbol for volatge

A

V

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16
Q

What is the equations to find power?

A

P = I x V

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17
Q

what can you do to induce voltage?

A

moving a magnet in or near a coil of wire, this is called electromagnetic induction

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18
Q

how does electromagnetic induction work?

A

as you move the magnet, the magnetic field through the coil changes - this change in the magnetic field induces voltage and a current flows through the wire if its part of a complete circuit.

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19
Q

what four factors affect the size of the induced voltage and current?

A

The strength of the magnet
the area of the coil
the number of turns on the coil
the speed of the movement

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20
Q

how do generators work?``

A

they generate current by rotating a magnet or a coil of wire

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21
Q

what are the 4 types of non renewable energy sources?

A

coal
oil
natural gas
nuclear fuels

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22
Q

what does non renewable mean?

A

they will all run out one day

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23
Q

what are the environmental problems with using non-renewables

A

they release CO2 - greenhouses effect/global warming
releases sulphur dioxide - acid rain
coal mining make a mess of the landscape
oil spillages causes serious environmental problems.
nuclear waste is very dangerous and difficult to dispose of.
nuclear power costs alot.
nuclear power always carried a risk of major catastrophies.

24
Q

what are the basic features of a typical power station

A

Fuel -> Boiler -> Turbine -> Generator -> National Grid

25
Q

What is the energy transfer in a typical power station?

A

Chemical -> Heat -> Kinetic -> Electric

26
Q

What does renewable mean?

A

it will never run out

27
Q

What are the 7 types of renewable energy?

A 
Hydroelectricity
Wave power
Tidal barrages
Wind power
Solar cells
Geothermal Energy
Biomass
28
Q

how does hydroelectricity work?

A

Hydroelectricity usually involves flooding a valley by building a big dam. Rain water is caught and allowed out through turbines.

29
Q

What are the advantages and disadvantages of hydroelectric power?

A
  • Big impact on the environment due to the flooding of the valley and possible loss of habitat for some species.
    + big advantage is immediate response to increased electricity demand - more water can be let out to generate more electricity.
  • Initial costs are high
    + minimal running costs
    + reliable energy source.
30
Q

how does wave power work?

A

waves can provide an up and down motion which can be used to drive a generator. Most electricity generated from wave power uses waves close to the shore. Waves further out in the ocean are much more powerful - offshore wave farms are now being developed to harness this power.

31
Q

What are the advantages and disadvantages of wave power?

A
  • fairly unreliable, since waves die out when the wind drops
  • never likely to provide energy on a large scale
    + it could be useful on small islands
32
Q

How do tidal barrages work?

A

Tidal barrages are big dams built across river estuaries, with turbines in them. as the tide comes in it fills up the estuary to a height to several metres. this water can then be allowed out through turbines at a controlled speed. it also drives the turbines on the way in.

33
Q

what are the advantages and disadvantages of tidal barrages?

A
  • it can only be used in a few of the most suitable estuaries
    + its a reliable energy source
    + potential to generate a significant amount of energy.
34
Q

how does wind power work?

A

wind turbines. each wind turbine has its own generator inside it so the electricity is generated directly from the wind turning the blades, which turn the generator.

35
Q

what are the advantages and disadvantages of wind power?

A

+ No pollution

  • Spoil the view
  • Noisy
  • Only work when its windy so its not possible to supply more electricity when theres extra demand
36
Q

How do solar cells work?

A

Use energy from the sun. solar cells usually used to generate electricity on a relatively small scale. solar power is often used in remote places where there aren’t many other ways to generate electricity, and satellites.

37
Q

what are the advantages and disadvantages of solar cells?

A
  • only reliable in sunny countries
  • only during the day
    + cost effective
38
Q

How does geothermal energy work?

A

It uses heat energy from underground. Water is pumped into pipes down to the hot rocks and it returns as steam to drive a generator. The source of much of the heat is the slow decay of various radioactive elements including uranium, deep inside the earth.

39
Q

How can we use biomass to produce energy?

A

It can be burnt in power stations to drive turbines and produce electricity.

40
Q

what are the advantages and disadvantages of using biomass for fuel?

A

+ Carbon neutral if you grow plants at the same rate you burn them.

41
Q

what does carbon neutral mean?

A

it takes in as much carbon dioxide as it produces.

42
Q

Why are some old power stations being taken out of use

A

Coal and oil supplies are running out so the old coal or oil burning power stations are being shut down and replaced by gas-fired power stations because they are quick to set up, theres plenty of gas, and gas doesn’t pollute as badly.

43
Q

What are the factors to consider when considering options for a new power station?

A 
Set up costs
Set-up time
Reliability issues
environmental issues
running/fuel costs
location issues
44
Q

What is the national grid?

A

A network of pylons and cables that cover the whole of britain, getting electricity to houses everywhere. it takes electrical energy from the power stations to just where its needed in homes and industry. it enables energy to be generated anywhere on the grid, and then be supplied anywhere else on the grid.

45
Q

What do you need to transmit the huge amount of power needed to provide electricity everywhere?

A

high voltage and high current.

46
Q

What are the problems with having a high current?

A

you lose lots of energy through heat in cables

47
Q

What do you use to change voltage?

A

Transformer

48
Q

what are transformers?

A

An iron core with two sets of coils of wire. step-up transformers have a bigger secondary coil. step-down transformers have a bigger primary coil

49
Q

How do you work out the output voltage from a transformer?

A

Primary voltage Primary coil
———————- = ——————-
Secondary voltage Secondary voltage

50
Q

What are the problems with transmitting high amounts of energy?

A

Lose a lot of power
Risk to people
could have long term health risks if you live near power lines

51
Q

How do you work out payback time?

A

annual saving

52
Q

What is payback time?

A

The payback time of an energy-saving solution is a measure of how cost-effective it is

53
Q

How can energy be measured?

A

joules (J) or Kilowatt Hours

54
Q

how do you work out power

A

power (W) = energy (J)
—————-
Time (sec)

55
Q

how many watts are in a kilowatt

A

1000

56
Q

How do you work out cost

A

cost = power (kW) x Time (Hours) x Cost of 1kWh

Physics - P1 (6 decks)

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