P1 Topic 3 - Waves And The Universe Flashcards
Go through and explain the different stages in the life cycle of a star.
1) Nebula - stars start as a clouds of dust and gas in space
2) Gravity forces the clouds to spiral in together, the gravitational potential energy is converted into heat energy and so the temperature rises.
3) Main Sequence Star - if the temperature becomes high enough, hydrogen nuclei will undergo nuclear fusion, which gives out a lot of energy. The nuclear fusion provides enough outwards force to counteract the gravitational pull of the star. This is a stable period that can last for billions of years.
4) Red Giant - as the hydrogen in the core runs out, the star swells and turns red as the surface cools.
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5a) Planetary Nebula - small to medium sized stars become unstable and eject their outer layers of dust and gas to form a planetary nebula.
6a) White Dwarf - a hot, dense solid core is left, which cools down and eventually disappears
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5b) Super Nova - big stars glow brightly, contracting and growing as they use up the last of the hydrogen, forming heavier elements until they explode in a super nova.
6b) Neutron Star - after the super nova throws the dust and gas into space, a very dense core is left, known as a neutron star.
7b) Black Hole - if the star is big enough, it will collapse under its own gravity and form a black hole.
Explain how a spectrometer works and what it is used for.
Spectrometers split up beams of light emitted from far away planets and stars using a slit, which diffracts the light into the spectrum.
Different elements absorb different wavelengths of light causing some wavelengths not to be emitted. The spectrum made will therefore have dark lines where light has been absorbed. These are called absorption spectra.
By comparing this to known spectra, the composition of planets and stars can be discovered.
Explain what red shift if, how it works and what it is used for?
Light from distant galaxies shifted towards the red end of the spectrum. This is because, as research has shown, galaxies are moving away from us, and as they do, the wavelengths of the light is stretched and therefore moves towards the red end of the spectrum.
It has been used to prove that the universe is expanding, probably due to the Big Bang.
What is Cosmic Microwave Background Radiation?
CMB radiation is low frequency microwave radiation coming from all over the universe.
CMB radiation can only be explained by the Big Bang Theory which is why it is currently the accepted explanation for the start of the Universe. As the Universe cools, so does the background radiation and it drops in frequency.
What is the Big Bang Theory and the Steady State Theory?
Big Bang Theory - all matter and energy compressed into a very small space, exploded and started expanding.
Steady State Theory - Universe has always existed, matter is created and destroyed, has no end and no beginning.
