A star is located at a distance of about 100 million light years from Earth. An astronomer plans to measure the distance of the
1 answer:
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Answer:
Emitted power will be equal to
Explanation:
It is given factory whistle can be heard up to a distance of R=2.5 km = 2500 m
Threshold of human hearing
We have to find the emitted power
Emitted power is equal to
So emitted power will be equal to
Answer:
True, True, False, False, False, False.
Explanation:
The refraction index of a material is given by the formula n=c/v, where c is the speed of light in vacuum and v the speed of light in the material. If a ray of light crosses a boundary between two transparent materials and the medium the ray enters has a larger index of refraction it means that in this new medium the speed of light is smaller than on the other one, and then its wavelength is also reduced since f must remain the same (and ), otherwise there is a discontinuity on number of vibrations per second, which cannot happen. So we know that:
1) The wavelength of the light decreases as it enters into the medium with the greater index of refraction. True.
2) The frequency of the light remains constant as it transitions between materials. True.
3) The speed of the light remains constant as it transitions between materials. False.
4) The speed of the light increases as it enters the medium with the greater index of refraction. False.
5) The frequency of the light decreases as it enters into the medium with the greater index of refraction. False.
6) The wavelength of the light remains constant as it transitions between materials. False.