P2 - Living For The Future Flashcards
What is our main source of energy?
The sun
What do photo cells do?
Generate electricity from sunlight
Summarise how solar cells work
1) They are made from silicone which is a semiconductor
2) It absorbs the sunlight, knocking electrons out of place
3) These flow around a circuit as electricity
What does the power output of a photocell depend on?
- Surface area
- Intensity of light
- Distance from light source
What are the advantages of photo cells?
- Low maintenance
- Long lasting
- No cables of food needed
- It is a renewable source
What are the disadvantages of photo cells?
When there is no sunlight there is no power
How do curved mirrors concentrate energy from the sun?
The shape of the mirrors reflects the light to a concentrated point, which spins a turbine producing energy
How does passive solar heating work?
Suns rays are absorbed by a Matt black surface which heats cold water to make hot water
How do wind turbines work?
The rotors spin due to the wind powering a generator
What are the advantages of wind energy?
- Renewable source
- Carbon neutral
- Cheap to run
What are the disadvantages of wind energy?
- You need 1500 turbines for 1 power station
- Visual and noise pollution
- Take a lot of space
What does the national grid?
This connects power stations to consumers
What are the three main steps of power stations?
1) Fuel is used to heat water to make steam
2) Steam moves blades of a turbine
3) The movement powers a generator
What is electromagnetic induction?
The creation of voltage and current in a wire which is experiencing a change in magnetic field
What can you do to an electromagnetic induction to get a bigger voltage and current?
1) Increase the strength of the magnet
2) Increase the number of turns in the coil
3) Increase the speed of movement
How does electromagnetic induction work?
Either a electric conductor (cool of wire) moves through a magnetic field or a magnetic field is put through a electric conductor
What do step up transformers do?
They increase the voltage from the generator onto the grid
What do step down transformers do?
They decrease the voltage from the grid to homes
Why are transformers needed?
They need to increase so less energy is lost on the grid then decrease it so it is safe for homes
What is the equation for total energy input?
Total energy input = useful energy output + waste energy out put
(The output is broken up into two parts)
What is the equation for efficiency?
Efficiency = useful energy output / total energy output (x100)
What do running costs depend on?
An appliances power rating
What is the equation for power?
Power = voltage x current
What is a kilowatt hour?
The amount of electrical energy converted by 1 kW appliance left in for 1 hour