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PHXI15:WAVES

354706 A sound wave of frequency \(n\) travels horizontally to the right. It is reflected from a large vertical plane surface moving to the left with speed \(v\). The speed of the sound in the medium is \(c\). Then,

1 The wavelength of the reflected wave is
\(\left[\dfrac{c}{n}\right]\left[\dfrac{c+v}{c-v}\right]\)

2 The frequency of the reflected wave is
\(\left[\dfrac{c+v}{c-v}\right] n\)

3 The number of beats heard by a stationary listener to the left to the reflecting surface is \(\dfrac{n v}{c-v}\)

4 The number of waves striking the surface per second is \(\left[\dfrac{c+v}{c}\right] n\)

PHXI15:WAVES

354707 A source of sound frequency \(256\;Hz\) is moving towards a wall with a velocity of \(5\;m{\rm{/}}s\). Velocity of sound is \(330\;m{\rm{/}}s\). The number of beats heard by an observer standing behind the source is nearly

1 \(\dfrac{256 \times 330}{325}-256\)

2 \(256-\dfrac{256 \times 330}{335}\)

3 \(\dfrac{256 \times 330}{325}-\dfrac{256 \times 330}{335}\)

4 \(\dfrac{256 \times 330}{325}-\dfrac{256 \times 330}{325}\)

PHXI15:WAVES

354708 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 \(\dfrac{v}{\sqrt{2}}\)

2 \(\dfrac{v}{3}\)

3 \(\dfrac{v}{4}\)

4 \(\dfrac{v}{2}\)

PHXI15:WAVES

354709 A band playing music at a frequency \(f\) is moving towards a wall at a speed \(v_{b}\). A motorist is following the band with a speed \(v_{m}\). If \(v\) be the speed of the sound, the expression for beat frequency heard by motorist is

1 \(\dfrac{v+v_{m}}{v+v_{b}} f\)

2 \(\dfrac{v+v_{m}}{v-v_{b}} f\)

3 \(\dfrac{2 v_{b}\left(v+v_{m}\right)}{v^{2}-v_{b}^{2}} f\)

4 \(\dfrac{2 v_{m}\left(v+v_{b}\right)}{v^{2}-v_{m}^{2}} f\)

PHXI15:WAVES

354710 An engine is moving towards a wall with a velocity \(50\;m{s^{ - 1}}\) emits a note of \(1.2kHz\). Speed of sound in air \( = 350\;m{s^{ - 1}}\). The frequency of the note after reflection from the wall as heard by the driver of the engine is

1 \(2.4kHz\)

2 \(0.24kHz\)

3 \(1.6kHz\)

4 \(1.2kHz\)

PHXI15:WAVES

354706 A sound wave of frequency \(n\) travels horizontally to the right. It is reflected from a large vertical plane surface moving to the left with speed \(v\). The speed of the sound in the medium is \(c\). Then,

1 The wavelength of the reflected wave is
\(\left[\dfrac{c}{n}\right]\left[\dfrac{c+v}{c-v}\right]\)

2 The frequency of the reflected wave is
\(\left[\dfrac{c+v}{c-v}\right] n\)

3 The number of beats heard by a stationary listener to the left to the reflecting surface is \(\dfrac{n v}{c-v}\)

4 The number of waves striking the surface per second is \(\left[\dfrac{c+v}{c}\right] n\)

PHXI15:WAVES

354707 A source of sound frequency \(256\;Hz\) is moving towards a wall with a velocity of \(5\;m{\rm{/}}s\). Velocity of sound is \(330\;m{\rm{/}}s\). The number of beats heard by an observer standing behind the source is nearly

1 \(\dfrac{256 \times 330}{325}-256\)

2 \(256-\dfrac{256 \times 330}{335}\)

3 \(\dfrac{256 \times 330}{325}-\dfrac{256 \times 330}{335}\)

4 \(\dfrac{256 \times 330}{325}-\dfrac{256 \times 330}{325}\)

PHXI15:WAVES

354708 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 \(\dfrac{v}{\sqrt{2}}\)

2 \(\dfrac{v}{3}\)

3 \(\dfrac{v}{4}\)

4 \(\dfrac{v}{2}\)

PHXI15:WAVES

354709 A band playing music at a frequency \(f\) is moving towards a wall at a speed \(v_{b}\). A motorist is following the band with a speed \(v_{m}\). If \(v\) be the speed of the sound, the expression for beat frequency heard by motorist is

1 \(\dfrac{v+v_{m}}{v+v_{b}} f\)

2 \(\dfrac{v+v_{m}}{v-v_{b}} f\)

3 \(\dfrac{2 v_{b}\left(v+v_{m}\right)}{v^{2}-v_{b}^{2}} f\)

4 \(\dfrac{2 v_{m}\left(v+v_{b}\right)}{v^{2}-v_{m}^{2}} f\)

PHXI15:WAVES

354710 An engine is moving towards a wall with a velocity \(50\;m{s^{ - 1}}\) emits a note of \(1.2kHz\). Speed of sound in air \( = 350\;m{s^{ - 1}}\). The frequency of the note after reflection from the wall as heard by the driver of the engine is

1 \(2.4kHz\)

2 \(0.24kHz\)

3 \(1.6kHz\)

4 \(1.2kHz\)

PHXI15:WAVES

354706 A sound wave of frequency \(n\) travels horizontally to the right. It is reflected from a large vertical plane surface moving to the left with speed \(v\). The speed of the sound in the medium is \(c\). Then,

1 The wavelength of the reflected wave is
\(\left[\dfrac{c}{n}\right]\left[\dfrac{c+v}{c-v}\right]\)

2 The frequency of the reflected wave is
\(\left[\dfrac{c+v}{c-v}\right] n\)

3 The number of beats heard by a stationary listener to the left to the reflecting surface is \(\dfrac{n v}{c-v}\)

4 The number of waves striking the surface per second is \(\left[\dfrac{c+v}{c}\right] n\)

PHXI15:WAVES

354707 A source of sound frequency \(256\;Hz\) is moving towards a wall with a velocity of \(5\;m{\rm{/}}s\). Velocity of sound is \(330\;m{\rm{/}}s\). The number of beats heard by an observer standing behind the source is nearly

1 \(\dfrac{256 \times 330}{325}-256\)

2 \(256-\dfrac{256 \times 330}{335}\)

3 \(\dfrac{256 \times 330}{325}-\dfrac{256 \times 330}{335}\)

4 \(\dfrac{256 \times 330}{325}-\dfrac{256 \times 330}{325}\)

PHXI15:WAVES

354708 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 \(\dfrac{v}{\sqrt{2}}\)

2 \(\dfrac{v}{3}\)

3 \(\dfrac{v}{4}\)

4 \(\dfrac{v}{2}\)

PHXI15:WAVES

354709 A band playing music at a frequency \(f\) is moving towards a wall at a speed \(v_{b}\). A motorist is following the band with a speed \(v_{m}\). If \(v\) be the speed of the sound, the expression for beat frequency heard by motorist is

1 \(\dfrac{v+v_{m}}{v+v_{b}} f\)

2 \(\dfrac{v+v_{m}}{v-v_{b}} f\)

3 \(\dfrac{2 v_{b}\left(v+v_{m}\right)}{v^{2}-v_{b}^{2}} f\)

4 \(\dfrac{2 v_{m}\left(v+v_{b}\right)}{v^{2}-v_{m}^{2}} f\)

PHXI15:WAVES

354710 An engine is moving towards a wall with a velocity \(50\;m{s^{ - 1}}\) emits a note of \(1.2kHz\). Speed of sound in air \( = 350\;m{s^{ - 1}}\). The frequency of the note after reflection from the wall as heard by the driver of the engine is

1 \(2.4kHz\)

2 \(0.24kHz\)

3 \(1.6kHz\)

4 \(1.2kHz\)

PHXI15:WAVES

354706 A sound wave of frequency \(n\) travels horizontally to the right. It is reflected from a large vertical plane surface moving to the left with speed \(v\). The speed of the sound in the medium is \(c\). Then,

1 The wavelength of the reflected wave is
\(\left[\dfrac{c}{n}\right]\left[\dfrac{c+v}{c-v}\right]\)

2 The frequency of the reflected wave is
\(\left[\dfrac{c+v}{c-v}\right] n\)

3 The number of beats heard by a stationary listener to the left to the reflecting surface is \(\dfrac{n v}{c-v}\)

4 The number of waves striking the surface per second is \(\left[\dfrac{c+v}{c}\right] n\)

PHXI15:WAVES

354707 A source of sound frequency \(256\;Hz\) is moving towards a wall with a velocity of \(5\;m{\rm{/}}s\). Velocity of sound is \(330\;m{\rm{/}}s\). The number of beats heard by an observer standing behind the source is nearly

1 \(\dfrac{256 \times 330}{325}-256\)

2 \(256-\dfrac{256 \times 330}{335}\)

3 \(\dfrac{256 \times 330}{325}-\dfrac{256 \times 330}{335}\)

4 \(\dfrac{256 \times 330}{325}-\dfrac{256 \times 330}{325}\)

PHXI15:WAVES

354708 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 \(\dfrac{v}{\sqrt{2}}\)

2 \(\dfrac{v}{3}\)

3 \(\dfrac{v}{4}\)

4 \(\dfrac{v}{2}\)

PHXI15:WAVES

354709 A band playing music at a frequency \(f\) is moving towards a wall at a speed \(v_{b}\). A motorist is following the band with a speed \(v_{m}\). If \(v\) be the speed of the sound, the expression for beat frequency heard by motorist is

1 \(\dfrac{v+v_{m}}{v+v_{b}} f\)

2 \(\dfrac{v+v_{m}}{v-v_{b}} f\)

3 \(\dfrac{2 v_{b}\left(v+v_{m}\right)}{v^{2}-v_{b}^{2}} f\)

4 \(\dfrac{2 v_{m}\left(v+v_{b}\right)}{v^{2}-v_{m}^{2}} f\)

PHXI15:WAVES

354710 An engine is moving towards a wall with a velocity \(50\;m{s^{ - 1}}\) emits a note of \(1.2kHz\). Speed of sound in air \( = 350\;m{s^{ - 1}}\). The frequency of the note after reflection from the wall as heard by the driver of the engine is

1 \(2.4kHz\)

2 \(0.24kHz\)

3 \(1.6kHz\)

4 \(1.2kHz\)

PHXI15:WAVES

354706 A sound wave of frequency \(n\) travels horizontally to the right. It is reflected from a large vertical plane surface moving to the left with speed \(v\). The speed of the sound in the medium is \(c\). Then,

1 The wavelength of the reflected wave is
\(\left[\dfrac{c}{n}\right]\left[\dfrac{c+v}{c-v}\right]\)

2 The frequency of the reflected wave is
\(\left[\dfrac{c+v}{c-v}\right] n\)

3 The number of beats heard by a stationary listener to the left to the reflecting surface is \(\dfrac{n v}{c-v}\)

4 The number of waves striking the surface per second is \(\left[\dfrac{c+v}{c}\right] n\)

PHXI15:WAVES

354707 A source of sound frequency \(256\;Hz\) is moving towards a wall with a velocity of \(5\;m{\rm{/}}s\). Velocity of sound is \(330\;m{\rm{/}}s\). The number of beats heard by an observer standing behind the source is nearly

1 \(\dfrac{256 \times 330}{325}-256\)

2 \(256-\dfrac{256 \times 330}{335}\)

3 \(\dfrac{256 \times 330}{325}-\dfrac{256 \times 330}{335}\)

4 \(\dfrac{256 \times 330}{325}-\dfrac{256 \times 330}{325}\)

PHXI15:WAVES

354708 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 \(\dfrac{v}{\sqrt{2}}\)

2 \(\dfrac{v}{3}\)

3 \(\dfrac{v}{4}\)

4 \(\dfrac{v}{2}\)

PHXI15:WAVES

354709 A band playing music at a frequency \(f\) is moving towards a wall at a speed \(v_{b}\). A motorist is following the band with a speed \(v_{m}\). If \(v\) be the speed of the sound, the expression for beat frequency heard by motorist is

1 \(\dfrac{v+v_{m}}{v+v_{b}} f\)

2 \(\dfrac{v+v_{m}}{v-v_{b}} f\)

3 \(\dfrac{2 v_{b}\left(v+v_{m}\right)}{v^{2}-v_{b}^{2}} f\)

4 \(\dfrac{2 v_{m}\left(v+v_{b}\right)}{v^{2}-v_{m}^{2}} f\)

PHXI15:WAVES

354710 An engine is moving towards a wall with a velocity \(50\;m{s^{ - 1}}\) emits a note of \(1.2kHz\). Speed of sound in air \( = 350\;m{s^{ - 1}}\). The frequency of the note after reflection from the wall as heard by the driver of the engine is

1 \(2.4kHz\)

2 \(0.24kHz\)

3 \(1.6kHz\)

4 \(1.2kHz\)

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