P2.6 Nucleur Fission and Nucleur Fusion Flashcards
What is nuclear fission?
When an atomic nucleus splits up to form two smaller nuclei
What is nuclear fission used for?
It produces a lot of energy, and is used in power stations to generate electricity
How does nuclear fission occur?
When a slow-moving neutron is absorbed into a uranium or plutonium nucleus - making it unstable and thus forcing them to split
What is released once a nucleus undergoes nuclear fission?
Neutrons
Why is there a chain reaction in nuclear fission?
Because the neutrons released can go be absorbed by other nuclei which results them to split and release neutrons and…
How is nuclear fission used as a way of generating electricity?
The energy released from nuclear fission is in the form of heat energy - the heat from nuclear fission is used to heat a coolant which is used to boil water, the steam produced is then used to turn a turbine which is connected to a generator
What are the problems with nuclear power? (3)
The radioactive waste produced can’t be thrown away and it’s difficult and expense to dispose of it safely, nuclear fuel is cheap but running costs are expensive, at risk of radiation leaks and/or major catastrophes like Chernobyl
What is nuclear fusion?
The combination of two nuclei which create larger nuclei
What produces more energy, fusion or fission?
Fusion
What are the benefits of fusion over fission as a source of energy?
Produces less waste and hydrogen is the product used in fusion which there is an abundance of
What are the drawbacks of fusion over fission as a source of energy?
Fusion requires a very high temp. and atm, fusion reactors use more energy to heat them up than they actually produce, you also need a very strong magnetic field so the hydrogen can be held at such a high temp. and pressure
How are stars formed?
Stars form from clouds of dust and gas, gravity forces the dust and gases to spiral together to form a protostar (where the GPE is converted into heat energy) - when the temp gets high enough, fusion occurs which gives out heat and light (this is a star)
How are planets formed?
Small masses of gas and dust around the star are pulled together to make planets which orbit the star
What phase of a stars life is the beginning of it’s life?
Main sequence stars - a star’s most stable point in it’s life, the heat created by fusion (pushing outwards) is equal to the force of graving pulling into the star
What fuses when the hydrogen runs out in the main sequence star?
Heavier nuclei are fused - all elements up to iron
What happens to a star (about the same size as our sun) when the hydrogen runs out?
It will expand into a red giant (red as it cools), which is unstable and ejects outer layers of dust and gas as planetary nebula
What is left behind when a red giant ejects it’s outer layers?
A white dwarf, which cools down to form a black dwarf and eventually disappears from sight
What happens to a star (larger than the size of our sun) when the hydrogen runs out?
A red super giant is formed - they are much bigger than red giants and burn for much longer
What eventually happens to red super giants?
They explode into supernovas, forming elements heavier than iron and ejecting them into the universe to form new planets and stars
What is made when a supernova explodes? (2)
A very dense core called a neutron star, or, if the star is a big enough, a black hole
