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Figure 6 shows a diagram of the Michelson-Morley interferometer that was used to try to detect the absolute motion of the Earth through the ether (either) - AQA - A-Level Physics - Question 4 - 2018 - Paper 7
Question 4
Figure 6 shows a diagram of the Michelson-Morley interferometer that was used to try to detect the absolute motion of the Earth through the ether (either). Light fr... show full transcript
Worked Solution & Example Answer:Figure 6 shows a diagram of the Michelson-Morley interferometer that was used to try to detect the absolute motion of the Earth through the ether (either) - AQA - A-Level Physics - Question 4 - 2018 - Paper 7
Step 1
Explain how the experiment provided a means of testing the idea that the Earth had an absolute motion relative to the ether.
Answer
The Michelson-Morley experiment was designed to detect the presence of the ether by observing interference patterns created by light traveling down two different paths. A shift in the fringe pattern was predicted due to the motion of the Earth through the ether, which would result in a difference in the time taken for light to travel along each path.
When the apparatus was rotated by 90°, the paths exchanged their roles. If the Earth were moving through the ether, a noticeable shift in the interference pattern would occur, reflecting a change in light travel times. However, the actual experiment found no significant shift, thereby contradicting the ether theory.
This outcome led to the conclusion that the Earth does not have an absolute motion through the ether, supporting the idea that the laws of physics are the same in all inertial frames.
Step 2
Step 3
Step 4
Determine the percentage of muons that reach the detector.
Answer
To calculate the time of flight for a muon traveling at 0.99c, we first find the time taken:
Using the speed of light, , we find:
Looking at the graph for the percentage remaining, we find that for a time of approximately , the percentage of muons remaining is approximately 68%.