354753
A stationary observer receives a sound of frequency \(2000\;Hz\). The variation of apparent frequency and time is shown. Find the speed of source. If velocity of sound is \(300\;m/s\).
1 \(66.6\;m/s\)
2 \(33.3\;m/s\)
3 \(27.3\;m/s\)
4 \(59.3\;m/s\)
Explanation:
As the apparent frequency is changing non linearly with time so it must be a two dimensional Doppler effects as shown in the figure. For AP, \(f=f_{0}\left(\dfrac{v}{v-v_{S} \cos \theta}\right)\) For PB \(f=f_{0}\left(\dfrac{v}{v+v_{S} \cos \theta}\right)\)
354754
When a source moves away from stationary observer with velocity \(v_{o}\) then apparent change in frequency is \(\Delta n_{1}\). When an observer approaches the stationary source with same velocity \(v\) then change in frequency is \(\Delta n_{2}\) then
354755
A source and an observer are at rest and there is no wind. The source emits sound of a wavelength \(\lambda\). Pick the wrong option when one of the following changes are made
1 If only the source moves the wavelength of received sound changes
2 If only the observer moves the wavelength of received sound changes
3 If only wind starts blowing the wavelength of received sound changes
4 If both source moves and wind blows the wavelength may not change
Explanation:
Wavelength of sound depends on wind and source velocity.
PHXI15:WAVES
354756
An observer moves towards a stationary source of sound with a speed 1/5th of the speed of sound. The wavelength and frequency of the source emitted \(\lambda\) and \(f\) are respectively. The apparent frequency and wavelength recorded by the observer are respectively
1 \(1.2 f, \lambda\)
2 \(f, 1.2 \lambda\)
3 \(0.8 f, 0.8 \lambda\)
4 \(1.2 f, 1.2 \lambda\)
Explanation:
The apparent frequency \(f^{\prime}=f\left(\dfrac{v+\dfrac{v}{5}}{v}\right)=\dfrac{6}{5} f=1.2 f\) \(v=\) Velocity of the sound As the source is stationary wavelength remains unchanged for observer.
PHXI15:WAVES
354757
Assertion : When observer moves away from the source the frequency of sound appears to decrease. Reason : The apparent frequency of sound depends on, whether the observer is moving towards source or away from source.
1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.
2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.
3 Assertion is correct but Reason is incorrect.
4 Assertion is incorrect but reason is correct.
Explanation:
The apparent frequency ( \(\left.f^{\prime}\right)\) is determined by the observer's velocity \(\left(v_{0}\right)\) and the source's velocity \(\left(v_{s}\right)\) relative to the speed of sound \((v)\). When the observer moves away (positive \(v_{0}\) ), the apparent frequency decreases, and when moving towards (negative \(v_{0}\) ), the apparent frequency increases. So correct option is (1).
354753
A stationary observer receives a sound of frequency \(2000\;Hz\). The variation of apparent frequency and time is shown. Find the speed of source. If velocity of sound is \(300\;m/s\).
1 \(66.6\;m/s\)
2 \(33.3\;m/s\)
3 \(27.3\;m/s\)
4 \(59.3\;m/s\)
Explanation:
As the apparent frequency is changing non linearly with time so it must be a two dimensional Doppler effects as shown in the figure. For AP, \(f=f_{0}\left(\dfrac{v}{v-v_{S} \cos \theta}\right)\) For PB \(f=f_{0}\left(\dfrac{v}{v+v_{S} \cos \theta}\right)\)
354754
When a source moves away from stationary observer with velocity \(v_{o}\) then apparent change in frequency is \(\Delta n_{1}\). When an observer approaches the stationary source with same velocity \(v\) then change in frequency is \(\Delta n_{2}\) then
354755
A source and an observer are at rest and there is no wind. The source emits sound of a wavelength \(\lambda\). Pick the wrong option when one of the following changes are made
1 If only the source moves the wavelength of received sound changes
2 If only the observer moves the wavelength of received sound changes
3 If only wind starts blowing the wavelength of received sound changes
4 If both source moves and wind blows the wavelength may not change
Explanation:
Wavelength of sound depends on wind and source velocity.
PHXI15:WAVES
354756
An observer moves towards a stationary source of sound with a speed 1/5th of the speed of sound. The wavelength and frequency of the source emitted \(\lambda\) and \(f\) are respectively. The apparent frequency and wavelength recorded by the observer are respectively
1 \(1.2 f, \lambda\)
2 \(f, 1.2 \lambda\)
3 \(0.8 f, 0.8 \lambda\)
4 \(1.2 f, 1.2 \lambda\)
Explanation:
The apparent frequency \(f^{\prime}=f\left(\dfrac{v+\dfrac{v}{5}}{v}\right)=\dfrac{6}{5} f=1.2 f\) \(v=\) Velocity of the sound As the source is stationary wavelength remains unchanged for observer.
PHXI15:WAVES
354757
Assertion : When observer moves away from the source the frequency of sound appears to decrease. Reason : The apparent frequency of sound depends on, whether the observer is moving towards source or away from source.
1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.
2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.
3 Assertion is correct but Reason is incorrect.
4 Assertion is incorrect but reason is correct.
Explanation:
The apparent frequency ( \(\left.f^{\prime}\right)\) is determined by the observer's velocity \(\left(v_{0}\right)\) and the source's velocity \(\left(v_{s}\right)\) relative to the speed of sound \((v)\). When the observer moves away (positive \(v_{0}\) ), the apparent frequency decreases, and when moving towards (negative \(v_{0}\) ), the apparent frequency increases. So correct option is (1).
354753
A stationary observer receives a sound of frequency \(2000\;Hz\). The variation of apparent frequency and time is shown. Find the speed of source. If velocity of sound is \(300\;m/s\).
1 \(66.6\;m/s\)
2 \(33.3\;m/s\)
3 \(27.3\;m/s\)
4 \(59.3\;m/s\)
Explanation:
As the apparent frequency is changing non linearly with time so it must be a two dimensional Doppler effects as shown in the figure. For AP, \(f=f_{0}\left(\dfrac{v}{v-v_{S} \cos \theta}\right)\) For PB \(f=f_{0}\left(\dfrac{v}{v+v_{S} \cos \theta}\right)\)
354754
When a source moves away from stationary observer with velocity \(v_{o}\) then apparent change in frequency is \(\Delta n_{1}\). When an observer approaches the stationary source with same velocity \(v\) then change in frequency is \(\Delta n_{2}\) then
354755
A source and an observer are at rest and there is no wind. The source emits sound of a wavelength \(\lambda\). Pick the wrong option when one of the following changes are made
1 If only the source moves the wavelength of received sound changes
2 If only the observer moves the wavelength of received sound changes
3 If only wind starts blowing the wavelength of received sound changes
4 If both source moves and wind blows the wavelength may not change
Explanation:
Wavelength of sound depends on wind and source velocity.
PHXI15:WAVES
354756
An observer moves towards a stationary source of sound with a speed 1/5th of the speed of sound. The wavelength and frequency of the source emitted \(\lambda\) and \(f\) are respectively. The apparent frequency and wavelength recorded by the observer are respectively
1 \(1.2 f, \lambda\)
2 \(f, 1.2 \lambda\)
3 \(0.8 f, 0.8 \lambda\)
4 \(1.2 f, 1.2 \lambda\)
Explanation:
The apparent frequency \(f^{\prime}=f\left(\dfrac{v+\dfrac{v}{5}}{v}\right)=\dfrac{6}{5} f=1.2 f\) \(v=\) Velocity of the sound As the source is stationary wavelength remains unchanged for observer.
PHXI15:WAVES
354757
Assertion : When observer moves away from the source the frequency of sound appears to decrease. Reason : The apparent frequency of sound depends on, whether the observer is moving towards source or away from source.
1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.
2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.
3 Assertion is correct but Reason is incorrect.
4 Assertion is incorrect but reason is correct.
Explanation:
The apparent frequency ( \(\left.f^{\prime}\right)\) is determined by the observer's velocity \(\left(v_{0}\right)\) and the source's velocity \(\left(v_{s}\right)\) relative to the speed of sound \((v)\). When the observer moves away (positive \(v_{0}\) ), the apparent frequency decreases, and when moving towards (negative \(v_{0}\) ), the apparent frequency increases. So correct option is (1).
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PHXI15:WAVES
354753
A stationary observer receives a sound of frequency \(2000\;Hz\). The variation of apparent frequency and time is shown. Find the speed of source. If velocity of sound is \(300\;m/s\).
1 \(66.6\;m/s\)
2 \(33.3\;m/s\)
3 \(27.3\;m/s\)
4 \(59.3\;m/s\)
Explanation:
As the apparent frequency is changing non linearly with time so it must be a two dimensional Doppler effects as shown in the figure. For AP, \(f=f_{0}\left(\dfrac{v}{v-v_{S} \cos \theta}\right)\) For PB \(f=f_{0}\left(\dfrac{v}{v+v_{S} \cos \theta}\right)\)
354754
When a source moves away from stationary observer with velocity \(v_{o}\) then apparent change in frequency is \(\Delta n_{1}\). When an observer approaches the stationary source with same velocity \(v\) then change in frequency is \(\Delta n_{2}\) then
354755
A source and an observer are at rest and there is no wind. The source emits sound of a wavelength \(\lambda\). Pick the wrong option when one of the following changes are made
1 If only the source moves the wavelength of received sound changes
2 If only the observer moves the wavelength of received sound changes
3 If only wind starts blowing the wavelength of received sound changes
4 If both source moves and wind blows the wavelength may not change
Explanation:
Wavelength of sound depends on wind and source velocity.
PHXI15:WAVES
354756
An observer moves towards a stationary source of sound with a speed 1/5th of the speed of sound. The wavelength and frequency of the source emitted \(\lambda\) and \(f\) are respectively. The apparent frequency and wavelength recorded by the observer are respectively
1 \(1.2 f, \lambda\)
2 \(f, 1.2 \lambda\)
3 \(0.8 f, 0.8 \lambda\)
4 \(1.2 f, 1.2 \lambda\)
Explanation:
The apparent frequency \(f^{\prime}=f\left(\dfrac{v+\dfrac{v}{5}}{v}\right)=\dfrac{6}{5} f=1.2 f\) \(v=\) Velocity of the sound As the source is stationary wavelength remains unchanged for observer.
PHXI15:WAVES
354757
Assertion : When observer moves away from the source the frequency of sound appears to decrease. Reason : The apparent frequency of sound depends on, whether the observer is moving towards source or away from source.
1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.
2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.
3 Assertion is correct but Reason is incorrect.
4 Assertion is incorrect but reason is correct.
Explanation:
The apparent frequency ( \(\left.f^{\prime}\right)\) is determined by the observer's velocity \(\left(v_{0}\right)\) and the source's velocity \(\left(v_{s}\right)\) relative to the speed of sound \((v)\). When the observer moves away (positive \(v_{0}\) ), the apparent frequency decreases, and when moving towards (negative \(v_{0}\) ), the apparent frequency increases. So correct option is (1).
354753
A stationary observer receives a sound of frequency \(2000\;Hz\). The variation of apparent frequency and time is shown. Find the speed of source. If velocity of sound is \(300\;m/s\).
1 \(66.6\;m/s\)
2 \(33.3\;m/s\)
3 \(27.3\;m/s\)
4 \(59.3\;m/s\)
Explanation:
As the apparent frequency is changing non linearly with time so it must be a two dimensional Doppler effects as shown in the figure. For AP, \(f=f_{0}\left(\dfrac{v}{v-v_{S} \cos \theta}\right)\) For PB \(f=f_{0}\left(\dfrac{v}{v+v_{S} \cos \theta}\right)\)
354754
When a source moves away from stationary observer with velocity \(v_{o}\) then apparent change in frequency is \(\Delta n_{1}\). When an observer approaches the stationary source with same velocity \(v\) then change in frequency is \(\Delta n_{2}\) then
354755
A source and an observer are at rest and there is no wind. The source emits sound of a wavelength \(\lambda\). Pick the wrong option when one of the following changes are made
1 If only the source moves the wavelength of received sound changes
2 If only the observer moves the wavelength of received sound changes
3 If only wind starts blowing the wavelength of received sound changes
4 If both source moves and wind blows the wavelength may not change
Explanation:
Wavelength of sound depends on wind and source velocity.
PHXI15:WAVES
354756
An observer moves towards a stationary source of sound with a speed 1/5th of the speed of sound. The wavelength and frequency of the source emitted \(\lambda\) and \(f\) are respectively. The apparent frequency and wavelength recorded by the observer are respectively
1 \(1.2 f, \lambda\)
2 \(f, 1.2 \lambda\)
3 \(0.8 f, 0.8 \lambda\)
4 \(1.2 f, 1.2 \lambda\)
Explanation:
The apparent frequency \(f^{\prime}=f\left(\dfrac{v+\dfrac{v}{5}}{v}\right)=\dfrac{6}{5} f=1.2 f\) \(v=\) Velocity of the sound As the source is stationary wavelength remains unchanged for observer.
PHXI15:WAVES
354757
Assertion : When observer moves away from the source the frequency of sound appears to decrease. Reason : The apparent frequency of sound depends on, whether the observer is moving towards source or away from source.
1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.
2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.
3 Assertion is correct but Reason is incorrect.
4 Assertion is incorrect but reason is correct.
Explanation:
The apparent frequency ( \(\left.f^{\prime}\right)\) is determined by the observer's velocity \(\left(v_{0}\right)\) and the source's velocity \(\left(v_{s}\right)\) relative to the speed of sound \((v)\). When the observer moves away (positive \(v_{0}\) ), the apparent frequency decreases, and when moving towards (negative \(v_{0}\) ), the apparent frequency increases. So correct option is (1).
