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Physics P1 > Waves And The Universe > Flashcards

Waves And The Universe Flashcards

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1
Q

Why can we see planets

A

Because they reflect sunlight

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2
Q

What is a galaxy

A

A collection of stars

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3
Q

What is a light year

A

The distance light would travel through a vacuum in one year
9.5x10(12) km

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4
Q

How do scientists start looking for signs of life in the universe

A

With Earth based telescopes or remote sensing techniques because slave exploration is very expensive

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5
Q

What is seti

A

Search for extraterrestrial intelligence
They’re looking for narrow bands of radio wavelengths coming from out of space
They look for meaningful signals in the space noise
They’ve been going for about 50 years
We constantly emit radio tv and radar into space to see if it’s detected
Scientists are now looking for laser signs in outer space

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6
Q

What do space crafts do

A

They carry probes and are sent to investigate planets and moons they carry instruments which can continuously record data about the conditions

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7
Q

What do robots do

A

They can take photos and collect rock and soil samples
Mars Viking Landers used robotic arms to collect soil samples and carried out experiments to see if there were signs of life the ph sent the results to earth to see if they could find any signs of life

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8
Q

What do scientists do when looking for life from other planets

A

They work out what all of the data means eg by analysing pictures
They also look for comets and asteroids to see if there could be life there

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9
Q

Why do we use space telescopes

A

So the earths atmosphere isn’t in the way because some waves are absorbed by the atmosphere

It helps to avoid light pollution which makes it hard to pick out dark objects and air pollution can reflect or absorb light coming in from space

They can see objects that are much fainter than can be seen from earth

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10
Q

What could the first telescopes detect

A

Visible light

They could only see close by objects and some objects aren’t detectable by juts visible

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11
Q

What are x ray telescopes used for

A

They are the best way to see violent high temperature events like exploding stars

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12
Q

What are radio telescopes used for

A

In Cygnus A they showed the structure of the Galaxy and how there’s two hot lobes moving apart from each other
They also were used to discover cosmic background radiation

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13
Q

Why are modern telescopes so good

A

Bigger telescopes give better resolution and can get more light and they have greater magnification which means we can see further into space
They help discover new galaxies which helps scientists discover more about their life cycle
Computers are used to create clearer and sharper images

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14
Q

What are spectrometers

A

It is a tool used to analyse the light given out by different galaxies
The light is directed through a slit and split into a spectrum
The light from different galaxies created different black lines Called absorption spectra and are caused by different wavelengths being absorbed eg by elements in the stars atmosphere

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15
Q

What do spectrometers show us

A

What different stars and galaxies are made up of
Each element has its own specific spectrum
Eg the sun has a similar absorption spectra to a hydrogen lamp so it is probably made of mostly hydrogen

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16
Q

What are emission spectra

A

When spectra have bright lines and are caused by extra light being emitted at those wavelengths

17
Q

How to make a spectrometer

A

Cut a 1mm wide slit on one of the box
Make a slit for the cd at a 45 degree angle on the side of the box
Make a hole to look through above the cd
Make sure the rainbow side of the cd is facing the hole you Look through
Hold the box up so it lets light in from a source

18
Q

What is the life cycle of a main sequence star

A 
Nebula
Main sequence star
Red giant
Planetary nebula
White dwarf
19
Q

What is a nebula

A

A cloud of dust and gas that forms a star

20
Q

How does a nebula become a main sequence star

A

The force of gravity makes the gas and dust spiral together and gravitational energy is converted to heat energy
When the temp is high enough thermonuclear emission happens to the hydrogen nuclei and helium nuclei are formed which give out huge amounts of energy

21
Q

What is a main sequence star

A

The heat created by the nuclear fusion gives an outward pressure that balances the force of gravity pulling everything inwards so the star is stable

22
Q

How is a red giant formed

A

When the hydrogen core begins to run out the star swells up and it becomes red as the surface cools

23
Q

How is a planetary nebula formed

A

The star becomes unstable and ejects it’s outer layer of dust and gas creating a planetary nebula

24
Q

What is a white dwarf

A

When the planetary nebula is formed it leaves behind a hot dense solid core which cools down and eventually disappears

25
Q

What is the life cycle of a big star

A 
Nebula 
Main sequence star
Red giant 
Supernova
Neutron star 
White dwarf
26
Q

How is a supernova formed

A

The red giant starts to glow brightly again and more fusion happens so they expand and contract lots of times forming heavier elements in nuclear reactions and eventually they explode to become a supernova

27
Q

How is a neutron star formed

A

The exploding supernova throws out layers of dust and gas into space leaving a very dense core called a neutron star

28
Q

How is a black hole formed

A

If the star is big enough the neutron star will become a black hole

29
Q

What is red shift

A

When we look at light from different galaxies the frequencies are all lower than expected and are shifted towards the red end of the spectrum
This suggests that the galaxies are all moving away from us very quickly in every direction
More distant galaxies have greater red shift this means they’re moving faster
This provides evidence that the universe is expanding which supports the big band theory

30
Q

What is cosmic microwave background radiation

A

A low frequency radiation coming from all parts of the electromagnetic spectrum
This supports the Big Bang theory because as the universe expands and cools the background radiation drops in frequency

31
Q

What is the Big Bang theory

A

All of the energy in the universe must’ve been compressed into a really small space and then exploded and started expanding
The expansion is still happening now and most scientists think the Big Bang was around 14 Million years ago

32
Q

What is the steady state theory

A

The universe has always been as big as it is now and always will be like this the universe is still expanding and matter is being created which causes red shift

Physics P1 (6 decks)

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