(B) Given: Velocity of sound, $v = 340 \ m/s$ Velocity of listener (car), $v_L = 17 \ m/s$ Velocity of source (bus), $v_S = ?$ Frequency of horn emitt

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(B) Given: Velocity of sound, $v = 340 \ m/s$ Velocity of listener (car), $v_L = 17 \ m/s$ Velocity of source (bus), $v_S = ?$ Frequency of horn emitted, $f = 640 \ Hz$ Apparent frequency, $f' = 680 \ Hz$ According to the Doppler effect, the apparent frequency $f'$ is given by: $f' = f \left( \frac{v + v_L}{v - v_S} \right)$ Substituting the given values: $680 = 640 \left( \frac{340 + 17}{340 - v_S} \right)$ Dividing both sides by $40$: $17 = 16 \left( \frac{357}{340 - v_S} \right)$ $17(340 - v_S) = 16 \times 357$ $5780 - 17v_S = 5712$ $17v_S = 5780 - 5712$ $17v_S = 68$ $v_S = 4 \ m/s$

Class 11 Physics Waves Doppler’s Effect

Medium

$A$ car is moving at a velocity of $17 \ m/s$ towards an approaching bus that blows a horn at a frequency of $640 \ Hz$ on a straight track. The frequency of this horn appears to be $680 \ Hz$ to the car driver. If the velocity of sound in air is $340 \ m/s$, then the velocity of the approaching bus is: (in $m/s$)

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A
$2$
B
$4$
C
$8$
D
$10$

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Waves

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Doppler’s Effect

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The frequency of a whistle of an engine is $600 \, Hz$ and it is moving with a speed of $30 \, m/s$ towards a stationary observer. The apparent frequency heard by the observer will be .... $Hz$ (velocity of sound $= 330 \, m/s$).

Medium

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$A$ boy is walking away from a wall towards an observer at a speed of $1\, m/s$ and blows a whistle whose frequency is $680\, Hz$. The number of beats heard by the observer per second is (Velocity of sound in air $= 340\, m/s$).

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When the observer moves towards a stationary source with velocity $V_1$, the apparent frequency of the emitted note is $F_1$. When the observer moves away from the source with velocity $V_1$, the apparent frequency is $F_2$. If $V$ is the speed of sound in air and $F_1/F_2 = 2$, then $V/V_1 =$

DifficultMHT CET 2026

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An observer moves towards a stationary source of sound with a speed $\frac{1}{5}^{\text{th}}$ of the speed of sound. The wavelength and frequency of the waves emitted by the source are $\lambda$ and $f$ respectively. The apparent frequency and wavelength heard by the observer are respectively,

MediumAIPMT 2003

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$A$ bat moving at $10\,ms^{-1}$ towards a wall sends a sound signal of $8000\,Hz$ towards it. On reflection, it hears a sound of frequency $f$. The value of $f$ in $Hz$ is close to (speed of sound $= 320\,ms^{-1}$)

DifficultJEE MAIN 2015

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The frequency of a whistle of an engine is $600 \, Hz$ and it is moving with a speed of $30 \, m/s$ towards a stationary observer. The apparent frequency heard by the observer will be .... $Hz$ (velocity of sound $= 330 \, m/s$).

$A$ boy is walking away from a wall towards an observer at a speed of $1\, m/s$ and blows a whistle whose frequency is $680\, Hz$. The number of beats heard by the observer per second is (Velocity of sound in air $= 340\, m/s$).

When the observer moves towards a stationary source with velocity $V_1$, the apparent frequency of the emitted note is $F_1$. When the observer moves away from the source with velocity $V_1$, the apparent frequency is $F_2$. If $V$ is the speed of sound in air and $F_1/F_2 = 2$, then $V/V_1 =$

An observer moves towards a stationary source of sound with a speed $\frac{1}{5}^{\text{th}}$ of the speed of sound. The wavelength and frequency of the waves emitted by the source are $\lambda$ and $f$ respectively. The apparent frequency and wavelength heard by the observer are respectively,

$A$ bat moving at $10\,ms^{-1}$ towards a wall sends a sound signal of $8000\,Hz$ towards it. On reflection, it hears a sound of frequency $f$. The value of $f$ in $Hz$ is close to (speed of sound $= 320\,ms^{-1}$)

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