What is the Doppler effect, and how is it produced? Cite two examples
What will be an ideal response?
Answer: The Doppler effect is the perceived change in frequency produced by relative motion between a receiver and the source of a wave. If a wave source approaches a receiver, waves encounter the receiver more often and a higher frequency is perceived. If a wave source recedes, waves encounter a receiver less often and a lower frequency is perceived. In the case of sound, when a siren from a fire engine or ambulance approaches you, its pitch is higher. When the vehicle passes, moving away, the pitch is lower. In the case of light, the spin of a star can be determined by noting that one edge has a slightly different color than the opposite edge. The edge spinning toward you will be slightly blue-shifted, while the edge spinning away from you is slightly red-shifted. So the edge turning toward you is bluish, and the edge turning away from you is redish.
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How does sonar work?
a. It measures the speed of sound by timing how long it takes sound to travel. b. It compares the speed of sound under different circumstances, by changing temperature or gas content. c. It compares the frequencies of the emitted and reflected sound wave. d. It measures the distance to underwater objects by bouncing sound waves off the objects. e. It measures the distance to objects in the upper atmosphere by timing the speed of sound to those objects.
In the context of the transitions in a hydrogen atom, the Lyman series lies in the infrared region
Indicate whether the statement is true or false
What percentage of the solar nebula's mass consisted of hydrogen and helium gases?
A) 0.5 percent B) 5 percent C) 50 percent D) 98 percent E) 100 percent
The buoyant force of the atmosphere on a body is equal to the
A) weight of air displaced. B) volume of air displaced. C) mass of the air displaced. D) all of the above E) none of the above