Wave Behavior C.5 Doppler Effect - 题库网 (tiku.one)

1#

A traveling source produces sound waves nearby a child. The wavefronts of the sound waves and the position of a child are seen in the figure below.

The frequency of the generated sound waves is f. Which of the following is correct for both the direction of motion of the source and the observed frequency of the sound waves by the child?

A. The direction of the motion is Toward the child ; Observed frequency is Less than f

B. The direction of the motion is Toward the child ; Observed frequency is More than f

C. The direction of the motion is Away from the child ; Observed frequency is Less than f

D. The direction of the motion is Away from the child ; Observed frequency is More than f

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2#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A car and a bicycle move in the same direction with speeds of $v_0$ and $v$ respectively as shown in the diagram below.

The car driver uses the horn to warn the cyclist. The frequencies of the sound heard by the car driver and cyclist are $f_o$ and $f$ respectively. Which of the following can be correct when $f_0
I. $v_0\,=\,10\,ms^{−1}$ and $v\,=\,5ms^−1$
II. $v_0\,=5\,ms^{−1}$ and $v\,=\,10ms^{−1}$
III. $v_0\,=\,10\,ms^{−1}$ and $v\,=\,10\,ms^{−1}$

A. $I$ only

B. $ III$ only

C. $I$ and $II$ only

D. $I$ and $III$ only

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3#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A geostationary satellite is used for TV broadcasting. It orbits so that a(pmd,bv)3ttg9 phzlm.;0 wwqu 7qx4 its position remains fixed au)(gb0,tappx3m4 l v7 9qmqdwhw;t.z bove a receiver on earth. It undergoes circular motion with a speed of v and the emitted frequency for a channel is f. Which of the following is correct?

A. The observed frequency by the receiver is less than f.

B. The observed frequency by the receiver is more than f.

C. The observed frequency by the receiver is equal to f.

D. The observed frequency by the receiver is equal to $f(\frac{v}{c}+1)$

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4#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A train is travelingxe:mr ),*mi di-i; wnv at $30\,ms^{−1}$ towards a stationary observer. It sounds a horn of frequency 450 Hz.
Which of the following statements is true about the observed frequency compared with the emitted frequency as the train approaches?

A. Observed frequency compared to emitted frequency is Lower ; Change in observed frequency over time is No change

B. Observed frequency compared to emitted frequency is Higher ; Change in observed frequency over time is Increases

C. Observed frequency compared to emitted frequency is Lower ; Change in observed frequency over time is Decreases

D. Observed frequency compared to emitted frequency is Higher ; Change in observed frequency over time is No change

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5#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A light source approaches a stationary receiver atia7 g -v3i)5sr1.bwqx nw5rku +yv-lz an increasing speed. The frequency of the emitted light is constant. Which graph 5+viiz-7l qsrk.vnwu-bra5x) 3 w1g y shows how the observed frequency f by receiver varies with the speed v of the light source?

A. B. C. D.

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6#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A fire truck’s siren emits a frequ6d97x7 tpz5a q w*epfcency of $f_0$. Starting from rest, it moves with constant acceleration and passes a stationary observer at $t=t_o$. Which graph shows the variation of observed frequency f by the stationary observer with time?

A. B. C. D.

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7#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A car drives along a straight road. Radio w 81 bcn+g;kt3bwdok :haves of frequency $f_o$ emitted from an antenna located at one end of the road are received by the car. The graph shows how the observed frequency $f$ by the car varies with time $t$.The graph shows how the observed frequency $f$ by the car varies with time $t$.

What can be stated for the motion of the car?

A. Stationary then approaches the antenna at a constant speed.

B. Moving at constant speed towards the antenna then stationary

C. Accelerates towards the antenna then moves with constant speed.

D. Accelerates towards the antenna then stationary.

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8#

填空题 ( 1.0 分) 切至整卷模式搜藏此题

1.(1)According to the big bang theory, the universe is expanding. One of the supporting pieces of evidence for this claim is the receding of galaxies from the earth and themselves. Which wave phenomenon is used in the discovery?

(2)One of the galaxies is receding from the earth at a constant speed. It emits radio waves in different frequencies. The difference between observed frequency by the receiver on the earth and emitted frequency $f$ from the galaxy is $Δf$. Sketch a graph that shows how $Δf$ varies with $f$. (no need to add values on the axis)

(3)State the assumption you made for the answer in (a) (ii)
2.(1)A stationary person by the side of a straight road records the frequency of the siren of an ambulance driving on the road. When the ambulance is not moving, the frequency is $f$.
The graph shows how the recorded frequency $′f′$ varies with time.

Describe the motion of the ambulance that would result in the graph above.
(2)The person decides to record the frequency of the horn of a car while moving in another car. A car of speed $24\,ms^{−1}$approaches another car of speed $s$ from behind on a level road.

The car behind uses its horn to clear its way. The frequency of the emitted sound wave is $10.0\,k\,Hz$ and the speed of the sound wave in air is $340\,ms^{−1}$. Calculate $s$, in $ms^{−1}$ if the detected frequency in the other car is $10.2\,k\,Hz$. s = $ms^{-1}$

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9#

填空题 ( 1.0 分) 切至整卷模式搜藏此题

An ultrasound source passes by a stationary sound detector wit6 bia5p sy jle(9m87gjh a constant speed ofy(aji pbe5gsm9l7j 68 $v$. The angle between the direction of the motion of the source and the line to the detector from the source is $30^{\circ}C$.

1.Describe the Doppler effect.
2.The frequency of the wave emitted by the source is 21 000 Hz. The average speed of ultrasound in the air is $350\,ms^{−1}$
For the orientation shown in the diagram, the detector receives an ultrasound that has a 27 Hz difference in the frequency from 21 000 Hz. Calculate the speed of the source. $u_s$ = $ms^{-1}$

3.The angle between the direction of the motion of the source and the detector is increased up to $90^{\circ}C$ at a steady rate. Sketch a graph that shows how the observed frequency $′f′$ by the detector varies with time $t$. (no need to add values on the axis)

$f_0$′ is the initial detected frequency and $f$ is the frequency of the wave emitted from the source.
2.(1)Another application of the doppler effect is calculating the speed of satellites.

A geostationary satellite is a satellite that is used for broadcasting. Its position is fixed above a stationary television receiver on earth. It undergoes circular motion with a speed of $8.0\,kms^{−1}$ and the emitted frequency for a channel is $3.0\times10^5\,Hz$. What is the frequency that should be set on the television on earth to be tuned with the channel? $10^5\,Hz$

2.While changing the position of a satellite, it approaches the earth at a constant speed. Explain, adding wavefronts to the diagram, any difference between emitted frequency from satellite and received frequency by the television.

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10#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A radio is placed on a turntable. The turntable rotates anticlockwise with constant angular frequency and the frequency of the generated sound waves is $f$. The frequency of sound waves is measured with a detector. The graph shows how the measured frequency $′f′$ varies with time $t$.

What can be the position of the radio at t=0s?

A. B. C. D.

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11#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Ultrasound incident on a moving blood cell reflected and received by a detector.

The frequency of an incident wave is $f$ and the measured frequency by the detector is $′f′$. The angle between the directions of the reflected wave and blood velocity $v$ is $θ$. Which of the following quantities is $′f′$ dependent on?

A. $v$ only

B. $v$ and $f$ only

C. $θ$ and $f$ only

D. $v$, $θ$ and $f$

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12#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A car of speed $3\,v$ approaches another car of speed $v$ from the rear on a level road.

The car with a speed of $3v$ uses its horn to clear its way. The frequency of the emitted sound wave is $f$ and the speed of the sound wave is $10v$. What is the observed frequency of the sound wave by an observer in the front car?

A. $\frac{2}{3}$

B. $\frac{11}{7}$

C. $\frac{9}{7}$

D. $\frac{10}{7}$

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