Change of frequency due to the Doppler effect is : $=n(\quad)$. This is independent of distance between source and observer.
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In a large room, a person receives direct sound waves from a source $120$ metres away from him. He also receives waves from the same source which reach him, being reflected from the $25$ metre high ceiling at a point halfway between them. The two waves interfere constructively for wavelength of
A man, standing between two cliffs, claps his hands and starts hearing a series of echoes at intervals of one second. If the speed of sound in air is $340 ms^{-1}$, the distance between the cliffs is .... $m$
The persistence of sound in a room after the source of sound is turned off is called reverberation. The measure of reverberation time is the time required for sound intensity to decrease by $60 \,dB$. It is given that the intensity of sound falls off as $I_0 \exp \left(-c_1 \alpha\right)$ where $I_0$ is the initial intensity, $c_1$ is a dimensionless constant with value $1 / 4$. Here, $\alpha$ is a positive constant which depends on the speed of sound, volume of the room, reverberation time, and the effective absorbing area $A_e$. The value of $A_e$ is the product of absorbing coefficient (with value between $0$ and $1,1$ being a perfect absorber) and the area of the room. For a concert hall of volume $600 \,m ^3$, the value of $A_e$ (in $m ^2$ ) required to give a reverberation time of $1 s$ is closest to (speed of sound in air $=340 \,m / s$ )
The extension in a string, obeying Hooke's law, is $x$. The speed of sound in the stretched string is $v$. If the extension in the string is increased to $1.5x$, the speed of sound will be
A wave travelling along the $x-$axis is described by the equation $y\left( {x,t} \right) = 0.005cos\left( {\alpha x - \beta t} \right)$ If the wavelength and the time period of the wave are $0.08\ m$ and $2.0\ s$, respectively, then $\alpha$ and $\beta$ in appropriate units are
A man standing on a platform observes that the frequency of the sound of a whistle emitted by a train drops by $140 Hz$. If the velocity of sound in air is $330 \,m / s$ and the speed of the train is $70 \,m / s$, the frequency of the whistle is .......... $Hz$