What do we call the rate of flow of electrical charge?
What can we describe as electrical pressure that gives a measure of the amount of energy transferred?
What is power?
How much energy is transferred per second
What is the unit of power and its symbol?
Name some sources of renewable energy
- Any of:
Name some disadvantages of wind turbines
- Not all days have the right amount of wind (not too little or too much)
- Lots of turbines are needed to produce the same amount of energy as a fossil-fuelled power station.
- Some people think that they spoil the landscape.
Which type of renewable energy uses the gravitational potential energy (GPE) stored in water?
Which type of renewable energy uses underground thermal energy?
Which type of renewable energy power station can be started and stopped very quickly?
What is the difference between wave and tidal power?
Wave power uses the vertical up and down movement of waves whereas tidal power uses the daily in and out movement of the tides.
Give some disadvantages of tidal power
- Tidal power is not constant (although it is predictable).
- The tidal barrages (dams) needed to generate electricity can cause problems for wildlife.
- Not all places with tides are suitable for tidal barrages.
Name a disadvantage of geothermal energy
Pollution from some gases dissolved in the steam that returns from underground.
What are renewable energy resources?
Resources that will not run out
Name four important non-renewable sources of energy
- Coal, oil, gas (the three fossil fuels)
- uranium (a nuclear fuel)
Name the three fossil fuels
State two problems caused by burning fossil fuels
- Carbon dioxide is released which contributes to global warming.
- Gases such as sulphur dioxide and nitrogen oxides contribute to acid rain.
Give an advantage of nuclear power
There are no emissions of carbon dioxide or other gases
Which is considered the cleanest of the fossil fuels?
Natural gas (does not contain sulfur and releases less carbon dioxide)
What is the main disadvantage of nuclear power?
It produces radioactive waste which can be dangerous for millions of years
Name some advantages of using non-renewable fuels rather than renewable sources of energy
- They produce cheaper electricity.
- They do not rely on the weather or the tides so electricity is available all the time.
- They can be built anywhere and do not rely on the availability of falling water, tides or a sunny climate.
What factors affect the size of the induced current in a generator?
- The number of turns of wire
- using an iron core inside the coil
- using stronger magnets
- moving the wire (or magnet) faster
How can you change the direction of the induced current in a generator?
- By moving the coil (or magnet) in the opposite direction.
- By reversing the direction of the magnetic field.
Dynamos produce dc electricity. What does dc mean?
Direct current only flows in one direction
Generators produce ac electricity. What does ac mean?
Alternating current flows in one direction then back again to and fro
How do power stations increase the strength of the magnets they use?
They use electricity to make electromagnets
What is the role of electrical transformers?
They change the size of an alternating voltage (either increasing or decreasing it). They do not work with dc.
What name is given to a transformer that increases ac voltage?
A step-up transformer
What name is given to a transformer that reduces ac voltage?
A step-down transformer
What is the National Grid?
The network of power stations, cables, pylons and transformers that transmits electrical energy from where it is produced to where it is used.
Why are step-up transformers used to increase the voltage to 400 000 V before electricity is sent around the country on pylons and wires?
Higher voltages are more efficient which results in less wasted energy
How many volts is electricity generated at by power stations?
25 000 V (25kV)
Where are step-down transformers used?
- Near where electricity is used.
- It is transmitted at 400 000 V but needs to be reduced to a safer level for use in homes, schools, and factories
What is the unit and symbol for energy?
What unit do electricity companies use to charge for the amount of electricity used?
Kilowatt-hour (kWh). Using a 1kW device for 1 hour uses 1kWh of electrical energy.
What is meant by payback-time?
It is the amount of time it takes for equipment to save the same amount of money that it cost to buy and install it.
Name some advantages of using low energy appliances
They use less energy so cost less to run and also result in less pollution from generating the electricity.