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14 Cards in this Set
- Front
- Back
The Figure shows an aeroplane being tracked by radar.
Which of these is used for radar? gamma rays infrared visible light microwaves radio waves. |
A radio waves |
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The radar operators use the Doppler effect to tell whether the plane is flying towards or away from the tower.
Explain how the observers in the tower can tell if the aeroplane is flying towards the tower. |
The wavelength of the returning/reflected waves will be shorter (travelling towards) OR the frequency of the returning waves will be longer. |
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The Figure shows the spectrum of light from two distant galaxies. Decide whether each of these statements is TRUE or FALSE. (a) The red end of the spectrum is the higher energy end of the spectrum. (b) The dark lines are missing wavelengths of light. |
(a) FALSE (b) TRUE |
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(c) The red end of the spectrum is the longer wavelength end of the spectrum. (d) The top spectrum is for the galaxy that is furthest away. (e) The bottom spectrum is for the galaxy that is moving fastest. |
(c) TRUE (d) FALSE (e) TRUE |
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The table shows the distance from Earth of different galaxies and the speed at which the galaxies are moving away from Earth. (a) Are there any anomalous values in this table? If so, which value(s)? (b) What does the data tell you about the distance to a galaxy and the speed it is moving away from Earth? (c) Explain what data scientists collected and what they measured to produce this table. |
(a) The speed of galaxy D.
(b) The further away a galaxy, the faster it is moving away from the Earth. (c) The scientists recorded/measured the spectrum of the galaxy and measured the red shift of the spectral lines. |
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The cosmic microwave background radiation (CMBR) is important evidence for the Big Bang theory. Explain what it is and why it is important. |
CMBR is microwave radiation that is found everywhere in the Universe, and is the same in all directions. Scientists predicted that if the Universe started with a Big Bang then radiation from shortly after the Big Bang would, after all this time, now be in the microwave region of the electromagnetic spectrum. Finding the CMBR was an important step in the Big Bang theory being accepted. Currently, the Big Bang is the only theory that explains the CMBR. |
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Some students investigate the Doppler effect. They use a loudspeaker emitting a sound with a frequency of 256 Hz and put this in a car that is driven along a straight racetrack at speeds of 10 mph, 20 mph and up to 70 mph. The frequency is picked up by a microphone and a computer displays the frequency received.The students record the results in a table, and work out the speed in m/s and the increase in frequency. They plot a graph of frequency increase against the speed of the car. (a) How can you tell that the car was driven towards the students and not away from them? (b) Which is the independent variable in this investigation? |
(a) The frequency would have decreased if the car was driven away OR the graph would have had negative values. (b) The speed. |
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(c) Describe the relationship between the frequency increase and the speed of the car. (d) Explain how the graph tells you this. (e) Use the graph to find the frequency increase at 29 m/s. (f) From your answer to (e) work out the frequency heard by the observers when the car was travelling at 28 m/s and explain whether the observers could hear the sound. |
(c) The increase in frequency is proportional to the speed of the car OR the frequency increases as the speed increases OR linear. (d) It is a straight line through the origin. (e) 22 Hz (f) 256+ 22 Hz = 278 Hz Observers can hear the sound because it is in the range of human hearing. |
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The Steady State theory is an alternative to the Big Bang theory. In the Steady State theory, the Universe expands and has always existed. As it expands,matter is created in parts of the Universe to keep the density of matter, like stars and galaxies, looking the same. What is the difference in the way that the Steady State theory and the Big Bang theory consider the origin of the Universe? |
Big Bang theory: Universe started as a point (and expanded). Steady State theory: Universe has no origin, it has always existed (and expanded). |
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Radiation detected from distant galaxies has a red shift. Explain what is meant by ‘red shift’. |
Wavelength increases (or frequency decreases) It is OK to say that the wavelength moves towards the red end of the spectrum, but not wavelength moves towards the red. |
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Explain whether the red shift evidence: (i) supportsthe Big Bang theory’ (ii)supportsthe Steady State theory. |
(i) Yes,because it shows the distant galaxies are moving away, which supports the suggestion that the universe is expanding. (ii) Yes,because it shows the distant galaxies are moving away, which supports the suggestion that the universe is expanding. |
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Suggest a reason why scientists cannot answer the question, ‘Why was the Universe created?’ |
There is not enough evidence OR it involves religious belief. |
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A monitor to measure the performance of a tennis player’s serve sends out microwaves towards the ball, and displays the speed of the ball. The microwaves have a wavelength of 12.5 cm. (a) What is the frequency of the microwaves?(speed of microwaves in air = 300 000 000 m/s) |
(a) Use the wave equation, velocity = frequency × wavelength. Frequency = 2 400 000 000 Hz. |
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Some microwaves are reflected from the ball, and detected by the monitor.
(b) Describe how this can be used to calculate the speed of the ball. |
Because the ball is travelling towards the detector, the reflected microwaves will be Doppler-shifted. The wavelength of the waves will be shorter. From the original wavelength of the waves and the Doppler-shifted/blue-shifted wavelength the speed of the ball can be calculated. |
