Doppler Effect
WAVES

173086 The driver of a car travelling with speed $30 \mathrm{~ms}^{-1}$ towards a hill sounds a horn of frequency 600 Hz. If the velocity of sound in air is $330 \mathrm{~ms}^{-1}$, the frequency of reflected sound as heard by driver is

1 $550 \mathrm{~Hz}$
2 $555.5 \mathrm{~Hz}$
3 $720 \mathrm{~Hz}$
4 $500 \mathrm{~Hz}$
WAVES

173087 A car is moving towards a high cliff. The car driver sounds a horn of frequency $f$. The reflected sound heard by the driver has a frequency $2 f$. If $v$ be the velocity of sound, then the velocity of the car, in the same velocity units, will be

1 $\frac{\mathrm{v}}{\sqrt{2}}$
2 $\frac{\mathrm{v}}{3}$
3 $\frac{\mathrm{v}}{4}$
4 $\frac{\mathrm{v}}{2}$
WAVES

173088 A whistle revolves in a circle with angular velocity $\omega=20 \mathrm{rad} / \mathrm{s}$ using a string of length 50 $\mathrm{cm}$. If the actual frequency of sound from the whistle is $385 \mathrm{~Hz}$, then the minimum frequency heard by the observer far away from the centre is (velocity of sound $v=340 \mathrm{~m} / \mathrm{s}$ )

1 $385 \mathrm{~Hz}$
2 $374 \mathrm{~Hz}$
3 $394 \mathrm{~Hz}$
4 $333 \mathrm{~Hz}$
WAVES

173090 A star which is emitting radiation at a wavelength of $5000 \AA$ is approaching the earth with a velocity of $1.50 \times 10^{6} \mathrm{~m} / \mathrm{s}$. The change in wavelength of the radiation as received on the earth is

1 $0.25 \AA$
2 $2.5 \AA$
3 $25 \AA$
4 $250 \AA$
WAVES

173091 Two trains move towards each other with the same speed. The speed of sound is $340 \mathrm{~m} / \mathrm{s}$. If the height of the tone of the whistle of one of them heard on the other changes 9/8 times, then the speed of each train should be

1 $20 \mathrm{~m} / \mathrm{s}$
2 $2 \mathrm{~m} / \mathrm{s}$
3 $200 \mathrm{~m} / \mathrm{s}$
4 $2000 \mathrm{~m} / \mathrm{s}$
[AIPMRT- 1991]
WAVES

173086 The driver of a car travelling with speed $30 \mathrm{~ms}^{-1}$ towards a hill sounds a horn of frequency 600 Hz. If the velocity of sound in air is $330 \mathrm{~ms}^{-1}$, the frequency of reflected sound as heard by driver is

1 $550 \mathrm{~Hz}$
2 $555.5 \mathrm{~Hz}$
3 $720 \mathrm{~Hz}$
4 $500 \mathrm{~Hz}$
WAVES

173087 A car is moving towards a high cliff. The car driver sounds a horn of frequency $f$. The reflected sound heard by the driver has a frequency $2 f$. If $v$ be the velocity of sound, then the velocity of the car, in the same velocity units, will be

1 $\frac{\mathrm{v}}{\sqrt{2}}$
2 $\frac{\mathrm{v}}{3}$
3 $\frac{\mathrm{v}}{4}$
4 $\frac{\mathrm{v}}{2}$
WAVES

173088 A whistle revolves in a circle with angular velocity $\omega=20 \mathrm{rad} / \mathrm{s}$ using a string of length 50 $\mathrm{cm}$. If the actual frequency of sound from the whistle is $385 \mathrm{~Hz}$, then the minimum frequency heard by the observer far away from the centre is (velocity of sound $v=340 \mathrm{~m} / \mathrm{s}$ )

1 $385 \mathrm{~Hz}$
2 $374 \mathrm{~Hz}$
3 $394 \mathrm{~Hz}$
4 $333 \mathrm{~Hz}$
WAVES

173090 A star which is emitting radiation at a wavelength of $5000 \AA$ is approaching the earth with a velocity of $1.50 \times 10^{6} \mathrm{~m} / \mathrm{s}$. The change in wavelength of the radiation as received on the earth is

1 $0.25 \AA$
2 $2.5 \AA$
3 $25 \AA$
4 $250 \AA$
WAVES

173091 Two trains move towards each other with the same speed. The speed of sound is $340 \mathrm{~m} / \mathrm{s}$. If the height of the tone of the whistle of one of them heard on the other changes 9/8 times, then the speed of each train should be

1 $20 \mathrm{~m} / \mathrm{s}$
2 $2 \mathrm{~m} / \mathrm{s}$
3 $200 \mathrm{~m} / \mathrm{s}$
4 $2000 \mathrm{~m} / \mathrm{s}$
[AIPMRT- 1991]
WAVES

173086 The driver of a car travelling with speed $30 \mathrm{~ms}^{-1}$ towards a hill sounds a horn of frequency 600 Hz. If the velocity of sound in air is $330 \mathrm{~ms}^{-1}$, the frequency of reflected sound as heard by driver is

1 $550 \mathrm{~Hz}$
2 $555.5 \mathrm{~Hz}$
3 $720 \mathrm{~Hz}$
4 $500 \mathrm{~Hz}$
WAVES

173087 A car is moving towards a high cliff. The car driver sounds a horn of frequency $f$. The reflected sound heard by the driver has a frequency $2 f$. If $v$ be the velocity of sound, then the velocity of the car, in the same velocity units, will be

1 $\frac{\mathrm{v}}{\sqrt{2}}$
2 $\frac{\mathrm{v}}{3}$
3 $\frac{\mathrm{v}}{4}$
4 $\frac{\mathrm{v}}{2}$
WAVES

173088 A whistle revolves in a circle with angular velocity $\omega=20 \mathrm{rad} / \mathrm{s}$ using a string of length 50 $\mathrm{cm}$. If the actual frequency of sound from the whistle is $385 \mathrm{~Hz}$, then the minimum frequency heard by the observer far away from the centre is (velocity of sound $v=340 \mathrm{~m} / \mathrm{s}$ )

1 $385 \mathrm{~Hz}$
2 $374 \mathrm{~Hz}$
3 $394 \mathrm{~Hz}$
4 $333 \mathrm{~Hz}$
WAVES

173090 A star which is emitting radiation at a wavelength of $5000 \AA$ is approaching the earth with a velocity of $1.50 \times 10^{6} \mathrm{~m} / \mathrm{s}$. The change in wavelength of the radiation as received on the earth is

1 $0.25 \AA$
2 $2.5 \AA$
3 $25 \AA$
4 $250 \AA$
WAVES

173091 Two trains move towards each other with the same speed. The speed of sound is $340 \mathrm{~m} / \mathrm{s}$. If the height of the tone of the whistle of one of them heard on the other changes 9/8 times, then the speed of each train should be

1 $20 \mathrm{~m} / \mathrm{s}$
2 $2 \mathrm{~m} / \mathrm{s}$
3 $200 \mathrm{~m} / \mathrm{s}$
4 $2000 \mathrm{~m} / \mathrm{s}$
[AIPMRT- 1991]
WAVES

173086 The driver of a car travelling with speed $30 \mathrm{~ms}^{-1}$ towards a hill sounds a horn of frequency 600 Hz. If the velocity of sound in air is $330 \mathrm{~ms}^{-1}$, the frequency of reflected sound as heard by driver is

1 $550 \mathrm{~Hz}$
2 $555.5 \mathrm{~Hz}$
3 $720 \mathrm{~Hz}$
4 $500 \mathrm{~Hz}$
WAVES

173087 A car is moving towards a high cliff. The car driver sounds a horn of frequency $f$. The reflected sound heard by the driver has a frequency $2 f$. If $v$ be the velocity of sound, then the velocity of the car, in the same velocity units, will be

1 $\frac{\mathrm{v}}{\sqrt{2}}$
2 $\frac{\mathrm{v}}{3}$
3 $\frac{\mathrm{v}}{4}$
4 $\frac{\mathrm{v}}{2}$
WAVES

173088 A whistle revolves in a circle with angular velocity $\omega=20 \mathrm{rad} / \mathrm{s}$ using a string of length 50 $\mathrm{cm}$. If the actual frequency of sound from the whistle is $385 \mathrm{~Hz}$, then the minimum frequency heard by the observer far away from the centre is (velocity of sound $v=340 \mathrm{~m} / \mathrm{s}$ )

1 $385 \mathrm{~Hz}$
2 $374 \mathrm{~Hz}$
3 $394 \mathrm{~Hz}$
4 $333 \mathrm{~Hz}$
WAVES

173090 A star which is emitting radiation at a wavelength of $5000 \AA$ is approaching the earth with a velocity of $1.50 \times 10^{6} \mathrm{~m} / \mathrm{s}$. The change in wavelength of the radiation as received on the earth is

1 $0.25 \AA$
2 $2.5 \AA$
3 $25 \AA$
4 $250 \AA$
WAVES

173091 Two trains move towards each other with the same speed. The speed of sound is $340 \mathrm{~m} / \mathrm{s}$. If the height of the tone of the whistle of one of them heard on the other changes 9/8 times, then the speed of each train should be

1 $20 \mathrm{~m} / \mathrm{s}$
2 $2 \mathrm{~m} / \mathrm{s}$
3 $200 \mathrm{~m} / \mathrm{s}$
4 $2000 \mathrm{~m} / \mathrm{s}$
[AIPMRT- 1991]
WAVES

173086 The driver of a car travelling with speed $30 \mathrm{~ms}^{-1}$ towards a hill sounds a horn of frequency 600 Hz. If the velocity of sound in air is $330 \mathrm{~ms}^{-1}$, the frequency of reflected sound as heard by driver is

1 $550 \mathrm{~Hz}$
2 $555.5 \mathrm{~Hz}$
3 $720 \mathrm{~Hz}$
4 $500 \mathrm{~Hz}$
WAVES

173087 A car is moving towards a high cliff. The car driver sounds a horn of frequency $f$. The reflected sound heard by the driver has a frequency $2 f$. If $v$ be the velocity of sound, then the velocity of the car, in the same velocity units, will be

1 $\frac{\mathrm{v}}{\sqrt{2}}$
2 $\frac{\mathrm{v}}{3}$
3 $\frac{\mathrm{v}}{4}$
4 $\frac{\mathrm{v}}{2}$
WAVES

173088 A whistle revolves in a circle with angular velocity $\omega=20 \mathrm{rad} / \mathrm{s}$ using a string of length 50 $\mathrm{cm}$. If the actual frequency of sound from the whistle is $385 \mathrm{~Hz}$, then the minimum frequency heard by the observer far away from the centre is (velocity of sound $v=340 \mathrm{~m} / \mathrm{s}$ )

1 $385 \mathrm{~Hz}$
2 $374 \mathrm{~Hz}$
3 $394 \mathrm{~Hz}$
4 $333 \mathrm{~Hz}$
WAVES

173090 A star which is emitting radiation at a wavelength of $5000 \AA$ is approaching the earth with a velocity of $1.50 \times 10^{6} \mathrm{~m} / \mathrm{s}$. The change in wavelength of the radiation as received on the earth is

1 $0.25 \AA$
2 $2.5 \AA$
3 $25 \AA$
4 $250 \AA$
WAVES

173091 Two trains move towards each other with the same speed. The speed of sound is $340 \mathrm{~m} / \mathrm{s}$. If the height of the tone of the whistle of one of them heard on the other changes 9/8 times, then the speed of each train should be

1 $20 \mathrm{~m} / \mathrm{s}$
2 $2 \mathrm{~m} / \mathrm{s}$
3 $200 \mathrm{~m} / \mathrm{s}$
4 $2000 \mathrm{~m} / \mathrm{s}$
[AIPMRT- 1991]