Doppler Effect
WAVES

172993 A motor car is approaching a road crossing with a speed of $108 \mathrm{~km} / \mathrm{h}$. A police standing near the crossing hears the frequency of the car's horn as $300 \mathrm{~Hz}$. The real frequency of the horn is [speed of sound in air $=332 \mathrm{~m} / \mathrm{s}$ ]

1 $300 \mathrm{~Hz}$
2 $332 \mathrm{~Hz}$
3 $273 \mathrm{~Hz}$
4 $400 \mathrm{~Hz}$
WAVES

172994 A star emitting light of wavelength $5896 \AA$ is moving away from the earth with a speed of $3600 \mathrm{~km} / \mathrm{s}$. The wavelength of the light observed on the earth will

1 decrease by $70.75 \AA$
2 increase by $70.75 \AA$
3 decrease by $150.50 \AA$
4 increase by $151.50 \AA$
WAVES

172995 The observer is moving with velocity ' $\mathrm{v}_{0}$ ' towards the stationary source of sound and then after crossing moves away from the source with velocity ' $v_{0}$ '. Assume that the medium through which the sound waves travel is at rest. If ' $v$ ' is the velocity of sound and ' $n$ ' is the frequency emitted by the source then the difference between apparent frequencies heard by the observer is

1 $\frac{2 \mathrm{nv}_{0}}{\mathrm{v}}$
2 $\frac{\mathrm{nv}_{0}}{\mathrm{v}}$
3 $\frac{\mathrm{v}}{2 \mathrm{nv}_{0}}$
4 $\frac{\mathrm{v}}{\mathrm{nv}_{0}}$
WAVES

172996 A train moving at a speed of $220 \mathrm{~ms}^{-1}$ towards a stationary object, emits a sound of frequency $1000 \mathrm{~Hz}$. Some of the sound reaching the object gets reflected back to the train as echo. The frequency of the echo as detected by the driver of the train is (speed of sound in air is $330 \mathrm{~ms}^{-1}$ )

1 $3500 \mathrm{~Hz}$
2 $4000 \mathrm{~Hz}$
3 $5000 \mathrm{~Hz}$
4 $3000 \mathrm{~Hz}$
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WAVES

172993 A motor car is approaching a road crossing with a speed of $108 \mathrm{~km} / \mathrm{h}$. A police standing near the crossing hears the frequency of the car's horn as $300 \mathrm{~Hz}$. The real frequency of the horn is [speed of sound in air $=332 \mathrm{~m} / \mathrm{s}$ ]

1 $300 \mathrm{~Hz}$
2 $332 \mathrm{~Hz}$
3 $273 \mathrm{~Hz}$
4 $400 \mathrm{~Hz}$
WAVES

172994 A star emitting light of wavelength $5896 \AA$ is moving away from the earth with a speed of $3600 \mathrm{~km} / \mathrm{s}$. The wavelength of the light observed on the earth will

1 decrease by $70.75 \AA$
2 increase by $70.75 \AA$
3 decrease by $150.50 \AA$
4 increase by $151.50 \AA$
WAVES

172995 The observer is moving with velocity ' $\mathrm{v}_{0}$ ' towards the stationary source of sound and then after crossing moves away from the source with velocity ' $v_{0}$ '. Assume that the medium through which the sound waves travel is at rest. If ' $v$ ' is the velocity of sound and ' $n$ ' is the frequency emitted by the source then the difference between apparent frequencies heard by the observer is

1 $\frac{2 \mathrm{nv}_{0}}{\mathrm{v}}$
2 $\frac{\mathrm{nv}_{0}}{\mathrm{v}}$
3 $\frac{\mathrm{v}}{2 \mathrm{nv}_{0}}$
4 $\frac{\mathrm{v}}{\mathrm{nv}_{0}}$
WAVES

172996 A train moving at a speed of $220 \mathrm{~ms}^{-1}$ towards a stationary object, emits a sound of frequency $1000 \mathrm{~Hz}$. Some of the sound reaching the object gets reflected back to the train as echo. The frequency of the echo as detected by the driver of the train is (speed of sound in air is $330 \mathrm{~ms}^{-1}$ )

1 $3500 \mathrm{~Hz}$
2 $4000 \mathrm{~Hz}$
3 $5000 \mathrm{~Hz}$
4 $3000 \mathrm{~Hz}$
WAVES

172993 A motor car is approaching a road crossing with a speed of $108 \mathrm{~km} / \mathrm{h}$. A police standing near the crossing hears the frequency of the car's horn as $300 \mathrm{~Hz}$. The real frequency of the horn is [speed of sound in air $=332 \mathrm{~m} / \mathrm{s}$ ]

1 $300 \mathrm{~Hz}$
2 $332 \mathrm{~Hz}$
3 $273 \mathrm{~Hz}$
4 $400 \mathrm{~Hz}$
WAVES

172994 A star emitting light of wavelength $5896 \AA$ is moving away from the earth with a speed of $3600 \mathrm{~km} / \mathrm{s}$. The wavelength of the light observed on the earth will

1 decrease by $70.75 \AA$
2 increase by $70.75 \AA$
3 decrease by $150.50 \AA$
4 increase by $151.50 \AA$
WAVES

172995 The observer is moving with velocity ' $\mathrm{v}_{0}$ ' towards the stationary source of sound and then after crossing moves away from the source with velocity ' $v_{0}$ '. Assume that the medium through which the sound waves travel is at rest. If ' $v$ ' is the velocity of sound and ' $n$ ' is the frequency emitted by the source then the difference between apparent frequencies heard by the observer is

1 $\frac{2 \mathrm{nv}_{0}}{\mathrm{v}}$
2 $\frac{\mathrm{nv}_{0}}{\mathrm{v}}$
3 $\frac{\mathrm{v}}{2 \mathrm{nv}_{0}}$
4 $\frac{\mathrm{v}}{\mathrm{nv}_{0}}$
WAVES

172996 A train moving at a speed of $220 \mathrm{~ms}^{-1}$ towards a stationary object, emits a sound of frequency $1000 \mathrm{~Hz}$. Some of the sound reaching the object gets reflected back to the train as echo. The frequency of the echo as detected by the driver of the train is (speed of sound in air is $330 \mathrm{~ms}^{-1}$ )

1 $3500 \mathrm{~Hz}$
2 $4000 \mathrm{~Hz}$
3 $5000 \mathrm{~Hz}$
4 $3000 \mathrm{~Hz}$
WAVES

172993 A motor car is approaching a road crossing with a speed of $108 \mathrm{~km} / \mathrm{h}$. A police standing near the crossing hears the frequency of the car's horn as $300 \mathrm{~Hz}$. The real frequency of the horn is [speed of sound in air $=332 \mathrm{~m} / \mathrm{s}$ ]

1 $300 \mathrm{~Hz}$
2 $332 \mathrm{~Hz}$
3 $273 \mathrm{~Hz}$
4 $400 \mathrm{~Hz}$
WAVES

172994 A star emitting light of wavelength $5896 \AA$ is moving away from the earth with a speed of $3600 \mathrm{~km} / \mathrm{s}$. The wavelength of the light observed on the earth will

1 decrease by $70.75 \AA$
2 increase by $70.75 \AA$
3 decrease by $150.50 \AA$
4 increase by $151.50 \AA$
WAVES

172995 The observer is moving with velocity ' $\mathrm{v}_{0}$ ' towards the stationary source of sound and then after crossing moves away from the source with velocity ' $v_{0}$ '. Assume that the medium through which the sound waves travel is at rest. If ' $v$ ' is the velocity of sound and ' $n$ ' is the frequency emitted by the source then the difference between apparent frequencies heard by the observer is

1 $\frac{2 \mathrm{nv}_{0}}{\mathrm{v}}$
2 $\frac{\mathrm{nv}_{0}}{\mathrm{v}}$
3 $\frac{\mathrm{v}}{2 \mathrm{nv}_{0}}$
4 $\frac{\mathrm{v}}{\mathrm{nv}_{0}}$
WAVES

172996 A train moving at a speed of $220 \mathrm{~ms}^{-1}$ towards a stationary object, emits a sound of frequency $1000 \mathrm{~Hz}$. Some of the sound reaching the object gets reflected back to the train as echo. The frequency of the echo as detected by the driver of the train is (speed of sound in air is $330 \mathrm{~ms}^{-1}$ )

1 $3500 \mathrm{~Hz}$
2 $4000 \mathrm{~Hz}$
3 $5000 \mathrm{~Hz}$
4 $3000 \mathrm{~Hz}$
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