Flashcards in Sustainable energy Deck (52):
What is energy measured in?
voltage x current (amps) =...
electrical power (watts)
Time x electrical power (watts) =
energy used (Joules)
efficiency = ( useful energy transferred ÷ energy supplied ) × 100
What is a primary source of energy?
A naturally occuring source
what effects can ionising radiation have on living cells?
It can make them cancerous
What is the voltage of the mains supply in Britain?
How are energy losses reduced by the National Grid?
Energy losses are reduced by distributing electricity at a high voltage, reducing heat losses.
What is the name of the process by which generators produce a voltage?
Electromagnetic induction is the process by which generators produce a voltage.
Renewable energy sources produce...
less pollution than burning fossil fuels
Which fossil fuel produces the most carbon dioxide?
Burning coal produces the most carbon dioxide.
In the atoms of a nuclear fuel, energy is released from...
changes in the nucleus.
What is the energy supplied in household electricity measured in ?
The energy supplied in household electricity is measured in kilowatt hours (kWh).
What is a secondary energy source ? Give an example.
A secondary energy source is one that is made using a primary resource. Electricity is secondary resource, and can be generated by a number of different primary sources.
What is a primary source of energy ? Give an example
A primary source of energy is one that occurs naturally.
Fossil fuels (coal, oil and gas), biofuels, wind, waves, solar radiation and nuclear fuels are all primary sources of energy.
What are Fossil fuels - how were they formed? How do they pollute?
Fossil fuels are formed over millions of years by the decay of dead organisms. When they are burned they produce a number of pollutants. A major pollutant formed is carbon dioxide, which contributes to global warming and climate change.
What happens electric current flows in a circuit,?
When an electric current flows in a circuit, energy is transferred from the power supply to the components in the circuit. The bigger the voltage, the more energy transferred.
If the voltage is 12V and the current is 5A, what is the power
If the voltage is 12V and the current is 5A, the power is 12 x 5 = 60W.
This means that 60J of energy is transferred per second.
How many W is 1kW (kilowatt) ? Therefore, 60J of energy is transferred per ? 1 watt = how many joules?
1 watt 60 joules? 1,000W is 1kW (kilowatt) 60J of energy is transferred per ? ( (1 watt = 1 joule per second).
The amount of electrical energy transferred to an appliance depends on what?
The amount of electrical energy transferred to an appliance depends on its power and the length of time it is switched on. The amount of mains electrical energy transferred is measured in kilowatt-hours, kWh. One unit is 1kWh.
Why is Electricity measured in Units (kilowatt-hours) instead of joules ?
Units (kilowatt-hours) are used instead of joules because a joule is too small a unit of energy.
Calculate the cost of using an electrical appliance if 5 units of electricity are used at a cost of 8p per unit?
total cost = number of units x cost per unit
For example, if 5 units of electricity are used at a cost of 8p per unit, the total cost will be 5 × 8 = 40p
How does a typical filament lamp work?
Ordinary electric lamps contain a thin metal filament that glows when electricity passes through it. However, most of the electrical energy is transferred as heat rather than light energy.
what is a sankey diagram?
a Sankey diagram is a flow diagram in which the width of the arrows are show proportionately to the flow quantity - the wider the arrows the more flow
In ordinary electric lamps most of the electrical energy is transferred as what?
most of the electrical energy is transferred as heat rather than light energy
The efficiency of a device such as a lamp can be calculated using what equation?
efficiency = (useful energy transferred ÷ energy supplied) × 100
What are the 4 stages that transfer energy to the turbine in a power station? At which stage is energy lost to the environment?
1) The energy produced by burning fuel is transferred as heat and
2) stored in water as steam.
3) The energy in steam is transferred to movement in a turbine
4) then to electrical energy in the turbine.
Energy is lost to the environment at each stage.
Name ways of generating renewable energy?
water energy, such as wave machines, tidal barrages and hydroelectric power
biomass energy, for example energy released from wood
What are some of the disadvantages of generating renewable energy?
For example, wind farms are noisy and may spoil the view of people who live near them. The amount of electricity generated depends on the strength of the wind. Also, if there is no wind, there is no electricity.
List some non-renewable energy resources, which will eventually run out.
fossil fuels, such as coal, oil and natural gas
nuclear fuels, such as uranium
Which Fossil fuels releases the most carbon dioxide when they burn and which the least?
Fossil fuels release carbon dioxide when they burn, which adds to the greenhouse effect and increases global warming. Of the three fossil fuels, coal produces the most carbon dioxide, for a given amount of energy released, while natural gas generates the least.
Is the fuel for nuclear power stations relatively cheap or expensive?
The fuel for nuclear power stations is relatively cheap.
What is costly about producing fuel from nuclear power stations ?
the power stations themselves are expensive to build. It is also very expensive to dismantle old nuclear power stations or store radioactive waste, which is a dangerous health hazard.
The main nuculear fuels are what? And what are they are?
uranium and plutonium, both of which are radioactive metals.
How do Nuclear fuels release energy?
Nuclear fuels are not burned to release energy. Instead, heat is released from changes in the nucleus.
Just as with power stations burning fossil fuels, the heat energy is used to boil water. The kinetic energy in the expanding steam spins turbines, which drive generators to produce electricity
Name two radioactive metals used in nuclear power stations?
The main nuclear fuels are uranium and plutonium, both of which are radioactive metals. .
What are the disadvantages of nuclear fuels?
Like fossil fuels, nuclear fuels are non-renewable energy resources. And if there is an accident, large amounts of radioactive material could be released into the environment. In addition, nuclear waste remains radioactive and is hazardous to health for thousands of years. It must be stored safely.
What are the advantages of nuclear fuels?
Unlike fossil fuels, nuclear fuels do not produce carbon dioxide.
When evaluating energy sources what must you consider?
When evaluating energy sources you must consider:
where the energy source is used (at home, in the work place or at a national level)
factors that affect the choice of energy source (economics, environmental impact, waste produced including carbon dioxide)
the advantages and disadvantages of the energy source
Energy is measured in?
Energy is measured in joules, J.
Power is measured in ?
Power is measured in watts, W
The rate of energy transfer is called ?
The rate of energy transfer is called the power.
what do Electricity meters measure?
Electricity meters measure the number of units of electricity used in a home or other building. Units (kilowatt-hours) are used instead of joules because a joule is too small a unit of energy.
The cost of the electricity used is calculated using what equation
total cost = number of units x cost per unit
if 5 units of electricity are used at a cost of 8p per unit, what will the total cost be?
if 5 units of electricity are used at a cost of 8p per unit, the total cost will be 5 × 8 = 40p
Write the equation to shows the relationship between energy transferred, power and time:
energy transfered (kilowatt-hour, kWh) = power (kilowatt, kW) x time (hour, h)
To convert from W to kW you must divide by what?
To convert from W to kW you must divide by 1000. For example, 2000W = 2000 ÷ 1000 = 2kW.
time is usually measured in seconds.
To convert from seconds to hours you must divide by what?
To convert from seconds to hours you must divide by 3600 (this is the number of seconds in 1 hour). For example, 1800s = 0.5 hours (1800 ÷ 3600)
The efficiency of the filament lamp is what %.
This means that how much electrical energy supplied is transferred as light energy. How much is transferred as heat energy.
The efficiency of the filament lamp is 10 ÷ 100 × 100 = 10%. This means that 10% of the electrical energy supplied is transferred as light energy. 90% is transferred as heat energy.
The efficiency of the energy-saving lamp is what % ?
This means that how much of the electrical energy supplied is transferred as light energy and how much is transferred as heat energy?
The efficiency of the energy-saving lamp is 75 ÷ 100 × 100 = 75%. This means that 75% of the electrical energy supplied is transferred as light energy. 25% is transferred as heat energy.