This Physics quiz is called 'Physics - Waves from Space' and it has been written by teachers to help you if you are studying the subject at senior high school. Playing educational quizzes is one of the most efficienct ways to learn if you are in the 11th or 12th grade - aged 16 to 18.
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The only way that we can learn about our universe is by using waves which come to Earth from space. The whole electromagnetic spectrum is represented - from mysterious gamma ray bursts, all the way to radio waves. But whichever waves you look at, you are always looking back in time.
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The light and heat from the Sun takes just over 8 minutes to reach the Earth so if the sun was to somehow be extinguished we on Earth would not find out until 8 minutes later. Light from the stars takes even longer. The closest star to our Solar System is Proxima Centauri - light takes just over 4 years to reach us from this star. When astronomers look at the most distant galaxies, they are seeing them as they were thousands of millions of years in the past.
So how can astronomers study the Universe using these waves from space? There are many advanced techniques but one of the fundamental ones is to use the Doppler effect. If a wave source is moving relative to an observer there will be a change in the observed wavelength and frequency. You can hear this when you are standing next to a highway with fast moving traffic. As the vehicles approach, they sound slightly different to when they are moving away. The pitch of the sound is higher as they approach because the waves are 'bunched up'. This shortens their wavelength and increases their frequency so they sound higher pitched than they do when they are not moving. As the vehicle passes and moves away, the waves get left behind and their wavelength is longer and their frequency is lower.
This happens with light too but is only detectable if something is moving at high speed as light waves have such a high velocity. Shorter wavelengths of light are bluer and longer ones are redder. Astronomers studying distant galaxies have observed an increase in the wavelength of light from most of them. The further away the galaxies are, the bigger the observed increase in wavelength. This effect is called red-shift and shows that the most distant galaxies are moving away from us at the fastest rates - the Universe is expanding.
Microwaves have played an important part in understanding the formation of the Universe. Cosmic microwave background radiation (CMBR) is a form of electromagnetic radiation filling the Universe. It comes from radiation that was present shortly after the big bang that has been cooling ever since. The ‘Big Bang’ theory is currently the only theory that can explain the existence of CMBR but who knows, tomorrow, or a hundred years from now, there could be new discoveries that change our understanding completely.
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1.
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Which of the following waves can be changed by the Doppler effect? |
|
[ ] |
Light waves |
[ ] |
Sound waves |
[ ] |
Microwaves |
[ ] |
All of the above |
|
|
2.
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When the source of a wave moves towards the observer, which of the following is not true? |
|
[ ] |
The frequency of the waves is higher |
[ ] |
If the wave is a light wave from a distant galaxy, the light is red-shifted |
[ ] |
The wavelength of the waves is less |
[ ] |
If the wave is a sound wave, the pitch sounds higher than it would if the source was stationary |
|
|
3.
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Galaxies emit (give out) many different types of wave. Which of the following would not be emitted by a galaxy? |
|
[ ] |
Sound |
[ ] |
Light |
[ ] |
Infrared |
[ ] |
X-rays |
|
|
4.
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Scientists measuring radio waves from a distant galaxy find the wavelength of the waves they have detected is longer than it should be. What is this called? |
|
[ ] |
Long-shift |
[ ] |
Wave-shift |
[ ] |
Red-shift |
[ ] |
Radio-shift |
|
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5.
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Scientists discovered that all of the distant galaxies they looked at showed red-shift. What does that tell us about the direction that most galaxies are moving? |
|
[ ] |
They are moving away from us |
[ ] |
They are moving towards us |
[ ] |
They are neither moving away nor towards us |
[ ] |
Red-shift gives no information about how galaxies are moving |
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6.
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What information does the red-shift of a galaxy give us? |
|
[ ] |
Its distance and number of stars in the galaxy |
[ ] |
Its speed and the number of stars it contains |
[ ] |
Its weight and the speed it is moving away |
[ ] |
Its distance and the speed of recession |
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7.
|
What conclusion can be drawn from the fact that nearly all galaxies are moving away from us? |
|
[ ] |
Galaxies repel each other like magnets |
[ ] |
The Universe is shaped like a hill and the galaxies are rolling down the hill |
[ ] |
Galaxies all have the same electrical charge |
[ ] |
The Universe is expanding |
|
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8.
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Which theory about the formation of the Universe is supported by its expansion? |
|
[ ] |
Steady State |
[ ] |
Big Bang |
[ ] |
Big Crunch |
[ ] |
The Oscillating Universe Theory |
|
|
9.
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In 1964, American radio astronomers Arno Penzias and Robert Wilson discovered the cosmic microwave background radiation (CMBR). Why was this an important discovery? |
|
[ ] |
It proved beyond doubt that the Big Bang theory was completely correct |
[ ] |
It proved that the Universe will never stop expanding |
[ ] |
It provided good evidence to support the Big Bang theory |
[ ] |
It completely disproved the Steady State theory |
|
|
10.
|
As the Universe gets older, what might happen to the cosmic microwave background radiation? |
|
[ ] |
Its wavelength could increase |
[ ] |
It may become stronger |
[ ] |
It will suddenly disappear |
[ ] |
It will turn into visible light |
|
|
1.
|
Which of the following waves can be changed by the Doppler effect? |
|
[ ] |
Light waves |
[ ] |
Sound waves |
[ ] |
Microwaves |
[x] |
All of the above |
|
|
2.
|
When the source of a wave moves towards the observer, which of the following is not true? |
|
[ ] |
The frequency of the waves is higher |
[x] |
If the wave is a light wave from a distant galaxy, the light is red-shifted |
[ ] |
The wavelength of the waves is less |
[ ] |
If the wave is a sound wave, the pitch sounds higher than it would if the source was stationary |
|
|
3.
|
Galaxies emit (give out) many different types of wave. Which of the following would not be emitted by a galaxy? |
|
[x] |
Sound |
[ ] |
Light |
[ ] |
Infrared |
[ ] |
X-rays |
|
|
4.
|
Scientists measuring radio waves from a distant galaxy find the wavelength of the waves they have detected is longer than it should be. What is this called? |
|
[ ] |
Long-shift |
[ ] |
Wave-shift |
[x] |
Red-shift |
[ ] |
Radio-shift |
|
|
5.
|
Scientists discovered that all of the distant galaxies they looked at showed red-shift. What does that tell us about the direction that most galaxies are moving? |
|
[x] |
They are moving away from us |
[ ] |
They are moving towards us |
[ ] |
They are neither moving away nor towards us |
[ ] |
Red-shift gives no information about how galaxies are moving |
|
|
6.
|
What information does the red-shift of a galaxy give us? |
|
[ ] |
Its distance and number of stars in the galaxy |
[ ] |
Its speed and the number of stars it contains |
[ ] |
Its weight and the speed it is moving away |
[x] |
Its distance and the speed of recession |
|
|
7.
|
What conclusion can be drawn from the fact that nearly all galaxies are moving away from us? |
|
[ ] |
Galaxies repel each other like magnets |
[ ] |
The Universe is shaped like a hill and the galaxies are rolling down the hill |
[ ] |
Galaxies all have the same electrical charge |
[x] |
The Universe is expanding |
|
|
8.
|
Which theory about the formation of the Universe is supported by its expansion? |
|
[ ] |
Steady State |
[x] |
Big Bang |
[ ] |
Big Crunch |
[ ] |
The Oscillating Universe Theory |
|
|
9.
|
In 1964, American radio astronomers Arno Penzias and Robert Wilson discovered the cosmic microwave background radiation (CMBR). Why was this an important discovery? |
|
[ ] |
It proved beyond doubt that the Big Bang theory was completely correct |
[ ] |
It proved that the Universe will never stop expanding |
[x] |
It provided good evidence to support the Big Bang theory |
[ ] |
It completely disproved the Steady State theory |
|
|
10.
|
As the Universe gets older, what might happen to the cosmic microwave background radiation? |
|
[x] |
Its wavelength could increase |
[ ] |
It may become stronger |
[ ] |
It will suddenly disappear |
[ ] |
It will turn into visible light |
|
|