P1 Topic 5 - Generation And Transmission Of Electricity Flashcards
What is voltage?
Voltage - is the electrical pressure giving a measure of the energy transferred.
What is current?
Current - the rate of flow of charge around a circuit. Electrons usually carry the charge - they are negatively charged particles.
What are A.C. and D.C.?
A.C. or alternating current keeps changing direction, the mains electricity is a.c.
D.C. or direct current always flows in the same direction, batteries and solar cells
What is electrical power?
Electrical Power - the energy transferred per second, units are Watts
How do you calculate power?
Power (W) = Voltage (V) x Current (I)
How do you measure the current and voltage of a circuit?
Current:
Use an ammeter
Place it in series (part of the circuit)
Voltage:
Use a voltmeter
Connect in parallel
How do you generate electricity using a coil of wire and a magnet?
You can induce a voltage in a conductor by moving a magnet in or near the coil of wire. This is called electromagnetic induction.
As you move the magnet, the magnetic field through the coil changes, this change in magnetic field induces voltage and causes a current to flow in the wire so long as it part of a complete circuit.
What four factors affect the size of the voltage induced by a magnet and coil of wire?
1) The strength of the magnet
2) The area of the coil
3) The number of turns on the coil
4) The speed of the movement
Name the four non-renewable energy resources.
Coal
Oil
Gas
Nuclear
What are the environmental problems of using non-renewable energy sources?
- All three fossil fuels release CO2 and CO.
> Contributes to global warming and greenhouse effect - Burning coal and oil releases sulphur dioxide
> Causes acid rain - Coal mining ruins the landscape, especially with open-cast mining
- Oil spillages cause serious cause serious environmental problems
- Nuclear power creates nuclear waste which is very dangerous and can be difficult to dispose of
- Nuclear power carries the risk of major catastrophes, such as Chernobyl
How do power stations make energy?
The coal, oil or gas is burnt (chemical energy into heat energy) and the heat is used to boil water into steams the steam turns a turbine (heat energy into kinetic energy) connected to a generator. As the generator turns, it induces a voltage (kinetic energy into electrical energy) using electromagnetic induction.
How do nuclear power stations make energy?
Nuclear fission is used to boil water (nuclear into heat).
The steam is used to turn a turbine (heat into kinetic).
The turbine is connected to a generator that induces a voltage with electromagnetic induction (kinetic into electrical).
What are the 7 renewable energy sources?
Hydroelectricity Wave power Tidal Barrages Wind power Solar cells Geothermal energy Burning natural waste
How does hydroelectricity produce electricity?
- A valley is usually flooded and then blocked with a big dam.
- Rain water is caught in the dam and allowed through turbines.
- The turbines are connected to generators which produce energy.
How does wave power produce electricity?
- Waves provide an up and down motion which forces air in and out of a turbine.
- The turbine is connected to a generator which makes power.
How do tidal barrages produce electricity?
- Big dams with turbines in them are built across estuaries.
- As the tides comes in, the height of the water in the estuary increases and the water can be let out slowly through the turbines.
How does wind power produce electricity?
- Each wind turbine has its own generator so electricity is produced directly when wind turns the blades.
How do solar cells produce electricity?
- As the sun shines on the cells, they generate a current from the light energy.
How does geothermal energy produce electricity?
- Cold water is pumped down to hot rocks near the surface (~7km).
- The water heats up and turns into steam and is pumped back to the surface.
- The steam turns a turbine which is connected to a generator.
How does biomass produce electricity?
- Biomass can be anything from farm waste, animal droppings, landfill rubbish or specially grown forests.
- The biomass is burnt and makes energy similarly to fossil fuels.
What are the advantages and disadvantages of the following renewable energy sources: Hydroelectricity Wave Power Tidal Barrages Wind Power Solar Cells Geothermal Energy Biomass
Hydroelectricity:
X Big impact on the environment as large areas have to be flooded which destroys the habitat of many species
X Initial costs are high
O Immediate response to increased electricity demand, more water can be let out through the turbines
O Minimal running costs
O Reliable source of energy
Wave Power:
X Fairly unreliable, waves stop when wind dies out
X Doesn’t produce much energy
O Useful for producing energy from small islands
O Offshore wave farms can be built further out in the ocean where the waves are more powerful
Tidal Barrages
X Can only be used on some estuaries that are suitable enough
O Reliable energy source
Wind Power
X Wind turbines spoil the view
X Only work when there is wind, so may not be able to supply electricity when demand is higher
O No pollution
Solar Cells
X Only produces energy during the daytime
X Usually used to generate energy on a small scale
O Reliable source of energy
Geothermal Energy
X Only possible where there are hot rocks near the surface
O High setup costs
O No environmental problems
Biomass
O The plants that grew to produce the waste took in CO2 from the atmosphere. When the waste is burnt, the same CO2 is released so there is no extra contribution. This means that burning biomass is carbon neutral.
What 6 factors have to be taken into consideration when building a power station?
Set-up costs Reliability issues Set-up time Running/fuel costs Environmental issues Location issues
What do transformers do and how do they work?
There are two types of transformers: step-up and step-down
Their purpose in the National Grid is to increase the voltage and minimise the loss of current and then decrease the voltage to safe levels for consumers.
They have two coils, a primary and secondary coil, which are joined by an iron core, the number of turns on each coil affects whether the voltage is stepped up or down.
If there are more turns on the secondary coil, the voltage is stepped up, on the other hand, if there are more turns on the primary coil then the voltage is stepped down.
What is the equation to calculate the output voltage from a transformer?
Primary voltage / Secondary voltage = Number of turns on primary / Number of turns on secondary
Or
Vp/Vs = Np/Ns
How do you calculate power using energy and time?
Power = Energy / Time
Or
W = J/s
How do you calculate the cost of using an electrical appliance using power, time in hours and cost of 1kWh?
Cost = Power x Time x Cost of 1kWh
Or
Cost = kW x h x Cost of 1kWh
