List of top Physics Questions on doppler effect

A passenger is sitting in a fast moving train. The engine of the train blows a whistle of frequency N. If the apparent frequency of sound heard by the passengers is \( N' \), then:
When both the source of sound and observer approach each other with a speed equal to 10% of the speed of sound, then the percentage change in frequency heard by the observer is nearly
A source (S) of sound has frequency\( 240 Hz\). When the observer (O) and the source move towards each other at a speed \(v\) with respect to the ground (as shown in Case 1 in the figure), the observer measures the frequency of the sound to be \(288 Hz\). However, when the observer and the source move away from each other at the same speed v with respect to the ground (as shown in Case 2 in the figure), the observer measures the frequency of sound to be \(n\) Hz. The value of \(n\) is _____.
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A galaxy is moving away from the Earth so that a spectral line at 6000 Å is observed at 6300 Å. Then the speed of the galaxy with respect to the Earth is
A train is moving with a speed of \(10 m/s\) towards a platform and blows a horn with frequency \(400 Hz\). Find the frequency heard by a passenger standing on the platform. Take speed of sound = \(310 m/s\).
A car P travelling at 20 \(ms^{–1}\) sounds its horn at a frequency of 400 Hz. Another car Q is travelling being the first car in the same direction with a velocity 40 \(ms^{–1}\) . The frequency heard by the passenger of the car Q is approximately [Take, velocity of sound = 360 \(ms^{–1}\) ]

A source of sound is moving away from a stationary observer with constant velocity 40 m/s. Find frequency heard by observer, if original frequency of source is 400 Hz and speed of sound in air is 360 m/s

S1 & S2 are sources of the sound of frequency 656 Hz. S1 is moving along OP and S2 is moving on the circle in an anticlockwise direction with a constant speed of 4√2 m\s. P is a detector that is fixed. Select the correct options (Vsound=300m\s)

circle in an anticlockwise direction

A source of sound emits sound waves at frequency \( f_0 \). It is moving towards an observer with fixed speed \( v_s \) (\( v_s < v \), where \( v \) is the speed of sound in air). If the observers were to move towards the source with speed \( v_0 \), one of the following two graphs (A and B) will give the correct variation of the frequency \( f \) heard by the observer as \( v_0 \) changes.

A bat emitting an ultrasonic wave of frequency \( 4.5 \times 10^4 \, \text{Hz} \) at speed of \( 6 \, \text{m/s} \) between two parallel walls. The two frequencies heard by the bat will be
A source and a detector move away from each other in absence of wind with a speed of 20 m/s with respect to the ground. If the detector detects a frequency of 1800 Hz of the sound coming from the source, then the original frequency of source considering speed of sound in air 340 m/s will be _________ Hz.
speeds of $20\, m/s$ and $15\, m/s$ relative to the ground. The first train sounds a whistle of frequency $600\, Hz$. The frequency of the whistle heard by a passenger in the second train before the train meets, is (the speed of sound in air is 340 m/s)
Two coherent monochromatic light beams of intensities ratio 1 : 4 are superposed. The ratio of maximum and minimum intensities in the resulting beam will be
A stationary source (see figure) emits sound waves of frequency $f$ towards a stationary wall. If an observer moving with speed u in a direction perpendicular to the wall measures a frequency $f' = \frac{11}{8} f $ at the instant shown, then $u$ is related to the speed of sound $V_S$ as
The air pressure at sea level is $ 101325 \,Pa $ . At the centre of a rarefaction of a sound wave in air, the pressure is $ 91000 \,Pa $ . Which is the most likely pressure at the centres of a compression of the same wave?
A source of sound $S$ emitting waves of frequency $100\, Hz$ and an observor $O$ are located at some distance from each other. The source is moving with a speed of $19.4\, m s^{-1}$ at an angle of $60^{\circ}$ with the source observer line as shown in the figure. The observor is at rest. The apparent frequency observed by the observer is (velocity of sound in air $330\, ms ^{-1}$ )
Two loudspeakers $M$ and $N$ are located $20\, m$ apart and emit sound at frequencies $118 \,Hz$ and $121 \,Hz$, respectively. A car is initially at a point $P, 1800\, m$ away from the midpoint $Q$ of the line $MN$ and moves towards $Q$ constantly at $60\, km / hr$ along the perpendicular bisector of $MN$. It crosses $Q$ and eventually reaches a point $R , 1800\, m$ away from $Q$. Let $v( t )$ represent the beat frequency measured by a person sitting in the car at time $t$. Let $v_{ P }, v _{ Q }$ and $v _{ R }$ be the beat frequencies measured at location $P , Q$ and $R$, respectively. The speed of sound in air is $330\, ms ^{-1} .$ Which of the following statement(s) is(are) true regarding the sound heard by the person?
A source and an observer are moving towards each other with a speed equal to $v/2$, where $v$ is the speed of sound. The source is emitting sound of frequency $n$. The frequency heard by one observer will be
The driver of a car travelling with speed $30\, m/sec$ towards a hill sounds a horn of frequency $600\, Hz.$ If the velocity of sound in air is $330\, m/s,$ the frequency of reflected sound as heard by driver is
Two sources $A$ and $B$ are sending notes of frequency $680 \,Hz$. A listener moves from $A$ and $B$ with-a constant velocity $u$. If the speed of sound in air is $340 \, ms^{-1}$ what must be the value of u so that he hears $10$ beats per second?
Dopplers effect in sound takes place when source and observer arc
With what velocity should an observer approach stationary sound source, so that the apparent frequency of sound appear to be double of the initial frequency? (given velocity of sound $= v$)
Sound waves in air are always longitudinal because,
A resonance air column of length $ 40\,\,cm $ resonates with a tuning fork of frequency $ 450\,\,Hz $ . Ignoring end correction, the velocity of sound in air will be:
Colours appear on a thin soap film and on soap bubbles due to the phenomenon of