What is our main source of energy at the moment?
Fossil fuels are _______ (they will run out one day)?
How can we conserve energy in the home?
- Use insulation in wall, ceilings, etc
- Get double glazing windows
- Switch appliances off when finished - do not leave them on standby
- Use draft excluders
How can we conserve energy in industry?
- Walk/ use public transport to get to work
- Switch appliances off
How can we conserve energy in transport?
- Share cars
- Encourage public transport
- Travel at an efficient speed
- Walk short distances instead of taking the car
Name three renewable energy sources and give the advantages and disadvantages of them
- Solar energy
- Advantage - A clean source of energy (no waste/pollutant gases or substances)
- Disadvantage - expensive and can only work during daylight hours
- Wind EnergyAdvantage - conditions for wind turbines are favourable in Britain
- Disadvantage - It is not always windy and turbines are unsightly and noisy
- Wave EnergyAdvantage - Reliable
- Disadvantage - Difficulties with construction, maintenance and energy conversion
- Geothermal energyAdvantage - clean source of energy
- Disadvantage - dependant on suitable sites
- Hydro-electricAdvantage - renewable, reliable and a clean source of energy
- Disadvantage - there are environmental objections to the building of dams
- Advantage - renewable
- Disadvantage - Growth is too slow to provide large amounts of fuel
In a thermal power station what energy transformation takes place in the boiler?
Chemical to heat
In a nuclear power station what energy transformation takes place in the nuclear reactor?
Nuclear to heat
In a hydro-electric power station what energy transformation takes place in the dam?
Gravitational potential energy to kinetic
In a nuclear power station, what kind of reactions take place in a nuclear reactor?
Nuclear fission reactions
Explain a nuclear chain reaction
- In a nuclear reactor, a neutron is fired at the nucleus of a uranium or plutonium atom causing the atom to break up into two fission fragments. (Every time this happens heat energy is released). Two or three more neutroms are also released from the split atom.
- The neutrons which are released hit other uranium or plutonium atoms causing them to break up and release more neutrons which go on to hit other uranium or plutonium atoms. This is known as a chain reaction
What is the main problem with nuclear reactors?
They produce radioactive waste
What happens in a pumped storage hydro-electric scheme?
The water which runs down the dam is pushed back up to the top so it can be used again. This is usually done at night when the demand for electricity is less and nuclear power stations are producing electricity which nobody will use. The electricity from the nuclear power station is used to push water back up the dam so the electriciy is not wasted
In every energy transformation some energy is lost as _____ or ______ energy?
heat or sound
How can we induce a voltage in a metal wire conductor?
- By moving a metal wire up or down between the opposite poles of a bar magnet
- By winding the metal wire into a coil then moving a bar magnet into or out of the coil
How do we make the induced voltage larger?
- Use a stronger magnet
- Move the wire or magnet faster
- Wind more turns of wire on the coil
What are transformers used for?
To change the size of an a.c. voltage
What are the main parts of a transformer?
- Primary coil
- Soft iron core
- Secondary coil
Step up transformers _________ the size of the a.c voltage?
Step down transformers _______ the size of the a.c. voltage?
Describe the stages in the transmission of electrical energy by the National Grid system
- Electricity from a power stations is sent to a step-up transformer which makes the voltage larger but the current smaller
- The electricity is sent around the country through overhead power lines which are held up by pylons - the connection of pylons across the country is called the National Grid
- The electricity arrives at a step-down transformer which makes the voltage smaller but the current larger.
- The electricity is passed to our homes via a substation through undergound power lines
Temperature tells us ....?
how hot or cold something is
What is temperature measured in?
Degrees celcius (°C)
The higher the temperature difference between the inside and outside of a house the _____ energy is lost?
How can energy by lost from a house?
- Conduction - happens mainly in solids. Particles vibrate against each other passing heat energy from one particle to the next
- Convection - Happens in liquids and gases. Hot particles move up while cold particles move down. This creates a convection current
- Radiation - Does not involve particles. Infra-red heat energy travels through gases and liquids as waves
How can we reduce the amount of energy lost through conduction?
- Insulate the upstairs ceilings
- Put foam in the walls
- Wall-to-wall carpets
- Double glazing
How can we reduce the amount of energy lost through convection?
- Seal doors and windows
How can we reduce the amount of energy lost through radiation?
- Put shiny surfaces in your insulation
- Paint your house white
What is the specific heat capacity of a substance?
The amount of heat energy needed to change the temperature of 1kg of the substance by 1 °C
When a substance melts, freezes, evaporates or condenses we say it is changing ______?
When a substance changes state what happens to the temperature of the substance?
It does not change