P2 Flashcards
Name one advantage and one disadvantage to using photocells ?
Advantages : sturdy , low maintain ace and produce no pollution
Disadvantages : no sunlight = no power
How do photocells work ?
They generate electricity from sunlight , they generate DC . Silicon atoms absorb some energy knocking some electrons loose , these electrons flow round a circuit and this is electricity
How do wind turbines work ?
Sun heats air which creates convection currents producing wind .
Wind turbines convert KE of moving air into electricity . The wind turns the blades which turn a generator
Name one advantage and disadvantage of wind turbines ?
Advantage = cheap to run , renewable and no pollution Disadvantage = noise pollution , visual pollution , amount needed to create same energy as fossil fuels
What is the national grid ?
A network of pylons and cable which covers the whole country
How does a power station work ?
Fossil fuels are boiled to produce high pressure steam which turns the turbine and the grenerator which converts the energy in to electricity and sends it to the national grid
Name 5 different types of fuels ?
Nuclear Fossil fuels Biomass Photocells Wind power
What is electromagnetic induction ?
The creation of a voltage in a wire which is experiencing a change in magnetic field
Transforming kinetic energy into electrical energy ( dynamo effect )
How can you increase the voltage (dynamo effect ) ?
The strength of the magnet
The number of turns on the coil
The speed of the movement
What is a step up transformer and a step down transformer ? Where are they used ?
Step up = increase voltage used from generator to grid
Step down = decrease voltage used from grid to homes
How do you calculate efficiency ?
Useful output divided by total energy input multiplied by 100
How do you calculate energy supplied ?
Power in KW X time in hours
How does the green house effect regulate earths temperature ?
Earth absorbs short EM radiation from sun , but emits some of this back in to space which cools earth down
This is absorbed by CO 2 methane and water vapour warming up the earth , the atmosphere acts as a insulating layer for earth
How does increased population increase greenhouse gasses ?
More fossil fuels burning ( cars ) More deforestation Respiration Increased cattle farming ( methane ) Power stations ( water vapour )
How has greenhouse effect led to climate change ?
Increased population leads to increased greenhouse gasses
A rise in CO 2 is causing global warming by increasing greenhouse effect
What are the 3 types of nuclear radiation ?
Alpha
Beta
Gamma
How ionising are Alpha Beta Gamma ?
Alpha - strongly ionising
Beta - moderately ionising
Gamma - weakly ionising
What can Alpha beta and gamma rays travel through ?
Alpha - sheet of paper stops radiation
Beta - aluminium stops radiation
Gamma - thick lead stops radiation
Name one use of Alpha , Beta and Gamma radiation ?
Alpha - smoke detectors
Beta - tracers and thickness gauges
Gamma - cancer treatment and medical cleaning
Name one advantage and disadvantage of nuclear power ?
Advantages - no CO2 produces , more energy produced , cheap
Disadvantages - expensive to build and maintain power stations , risk of leaks and explosions
How do you dispose of nuclear power safely ?
It stays radioactive for a long period of time so needs to be buried under ground in glass blocks to avoid leaks and explosions
Name the planets in order ?
Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Pluto
What force keeps planets orbiting the sun ?
Centripetal force
Why do scientists think that the moon was created by a collision with earth from another planet ?
Moon is lower density
Moon rocks contains few rocks which evaporate at low temps suggesting the moon was formed of hot material
What is a light year ?
Measure of distance in space
Name 2 advantages and disadvantages of unmanned space travel ?
Advantages - don’t have to carry food, water , and oxygen . Can withstand lethal conditions to humans . No people to take up room .
Disadvantages- probes can’t think for themselves , can’t do maintain without a astronaut there
Why do scientists believe the earth started with a bang ?
The universe was very small to begin with but then an explosion happened which caused it to expand - it’s still expanding now
The Big Bang theory allows scientists to guess the age of universe due to rate of expansion
What are the advantages and disadvantages of off peak electricity?
Advantages - cost effective for the electricity company as power stations can’t be turned of at night so it is useful to have a need for electricity at night also cheaper for costumes to buy electricity during off peak times
Disadvantages - increased risk of fire , can’t enjoy using electricity during day due to off peak hours
What was the copernican model ?
The copernican model states that all the planets orbit the sun , which is the centre of the universe in perfect circles
The model was introduced in 1543
What did Galileo discover ?
Galileo was studying Jupiter with a telescope which was advanced to that of copernican model he saw stars that never moved away from Jupiter which suggested there were moons orbiting Jupiter he also noticed that Venus had phases
Why were both the copernican model and Galileo condemned by the church and not beloved by people ? What changed their opinions ?
It was against the bible which says that earth is at the centre of the earth .
Evidence increased due to technological advances
What is the life cycle of stars ?
Clouds of dust - force of gravity makes gas and dust spiral together to form a protostar - when temp gets high enough the hydrogen nuclei undergo thermonuclear fusion forming helium nuclei and give out masses of heat main sequence star is formed - hydrogen runs out and star swells into red giant to be continued on another flash card
What happens to a small red giant ?
It becomes unstable and ejects it’s outer layer of dust and gas becoming a planetary nebula - leaving behind a white dwarf which cools and fades away
What happens to a big red supergiant ?
They undergo more fusion and expand then eventually explode resulting in a supernova - the exploding supernova throws outer layer into space leaving an dense neutron star - if big enough it will become a black hole
Why is there an asteroid belt between Jupiter and mars ?
The gravitational attraction of Jupiter disrupts the formation of a planet
What actions could be taken to reduce the threat of NEOs ?
- surveys by telescope
- monitoring satellites
- deflection by explosion
What are the properties of a black hole ?
- large mass but small volume and high density
- strong gravitational attraction due to large mass
What are medical tracers and how do they work ?
Medical traders are used to see if the body is working properly
Radioactive source is injected or swallowed and it’s progress can be detected using an external radiation detector .
Beta or gamma are used as the radiation passes out of the body
Why is electricity transformed to high voltage not high current before distribution?
You need either a high voltage or current ,but a high current is inefficient as it gets hot and all the wheat energy goes to waste ,so it is therefore cheaper to increase voltage to keep current low meaning less heat is wasted so it is more efficient
How is electricity created in a generator?
A coil of wire is rotated in a magnetic field , as the coil cuts through the magnetic field the relative motion causes current to be generated in the wire . AC is generated as every half turn the coil is changing direction (sometimes heading to south sometimes North Pole )
