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
What is the equation for energy supplied?
Energy supplied = power x time
What is the equation for cost?
Cost = number of units x price per unit
What is off peak electricity?
Electricity supplied during the night
What are the advantages with off peak electricity?
- Cost effective as power stations can’t be turned off
- Cheaper for consumer
What are the disadvantages of off peak electricity?
- Increase risk that appliances are on at night
- You may change your lifestyle
What are the four steps of the greenhouse effect?
1) Energy from the sun is absorbed by the earth
2) The earth radiates heat
3) The radiation is absorbed by greenhouse gases
4) This is then re radiated in all directions
What are the three types of nuclear radiation that cause ionisation?
- Alpha
- Beta
- Gamma
What are alpha particles like?
- Two protons and neutrons
- Big and heavy
- Stopped by skin or paper
- Strongly ionising
What are beta particles like?
- Electrons
- Small and fast
- Stopped by a few millimetres of aluminium
- Moderately ionising
What are gamma rays like?
- Electromagnetic radiation (wave)
- No mass or charge
- Stopped by a few centimetres of lead
- Weakly ionising
How do smoke detectors work?
1) They have a weak source of alpha radiation close to two electrodes
2) The radiation ionised the air
3) If there is smoke this will absorb the radiation and the current stops sounding an alarm
How do thickness gauges work?
- Beta is put through the paper
- If it is too thick the radiation goes down and if it is too thin it goes up
- This make it change to be correct thickness
How does medical sterilisation work?
Gamma kills all living cells so it will be able to sterilise equipment when hit
How is uranium used a a fuel?
The uranium splits into two releasing energy, this is used to heat the water just like in a power station
What are the advantages with nuclear power?
- Carbon neutral
- More energy
- Relatively cheap
What are the disadvantages of nuclear power?
- Expensive to build
- Dangerous
- Plenty of uranium
What is the best way to protect yourself from nuclear radiation?
Lead suit
How do people dispose of radioactive waste?
They bury them in secure places as they have a long half life so they last a long time
What is orbit do planets take?
Elliptical
What are the order of planets?
Mercury Venus Earth Mars Asteroids Jupiter Saturn Uranus Neptune (Mad Vampires Eat Mangoes And Jump Straight Up Noses)
How is the solar system held together?
Gravitational attraction
Which two planets do asteroids orbit between?
Mars and Jupiter
What are comets?
Balls of rock, dust or ice which orbit the sun at an elliptical orbit
What are near earth objects (NEOs)?
They are asteroids or comets that are on a collision course
How was the moon thought to have formed?
A mars sized planet hit into the earth causing debris which is the moon
What is a light year equal to in km?
9 460 000 000 000km
What happens when some stars explode?
Can leave black holes
What are the two means of exploring space?
- Manned spacecrafts
- Unmanned spacecrafts
What are the advantages of manned spacecrafts?
- Easier to get more information
- Much more reliable
What are the disadvantages of manned space crafts?
- It can be dangerous
- It is very expensive
What are the advantages of non manned spacecrafts?
- Much cheaper to make
- Stay in space for longer
What are the disadvantages of non manned spacecrafts?
- Problems could occur that can be solved easily
- Harder to find discoveries
How is the universe saw to be expanding?
- Distant galaxies have had red shifts (frequencies are lower than normal)
- There are microwaves (thought to be from Big Bang)
What are the nine steps of the life cycle of a star?
1) Cloud of dust and gas
2) Force of gravity form a protostar
3) Temperature will get high enough that a hydrogen nuclei undergoes thermonuclear fusion and forms a helium nuclei. This makes a main sequence star
4) The hydrogen runs out and swells into a red giant
SMALL STARS
5) The outer layer is ejects dust and gas making a planetary nebula
6) This leaves a hot, dense, solid core, which is a white dwarf
BIG STARS
7) Red supergiants expand and contract until they explode forming a supernova
8) When he supernova explodes it throws dust and gas leaving a dense core which is a neutron star
9) When this is big enough it will become a black hole
What did Ancient Greeks think the universe was like?
The earth was in the centre
What was Copernican’s model of the universe?
The sun was at the centre this was because of the phases of Venus
