Waves practice · Medium

When a sound source is moving towards a stationary observer :

Assertion (A): A driver under water is unable to hear the sound produced in air.
Reason (R): The sound produced in air undergoes reflection at the water surface.

Two identical strings $A$ and $B$, have nearly the same tension. When they both vibrate in their fundamental resonant modes, there is a beat frequency of $3 {~Hz}$. When string $B$ is tightened slightly, to increase the tension, the beat frequency becomes $6 {~Hz}$. This means

Learned Indian classical vocalists do not like the accompaniment of a harmonium because

Assertion: Description of sound as pressure wave is preferred over displacement wave.
Reason: Sound sensors (ear or mike) detect pressure changes.

The linear density of a vibrating string is $1.3 \times 10^{-4} \mathrm{~kg ~m}^{-1}.$ A transverse wave is propagating on the string and its described by the equation $y=0.021 \sin (x+30 t)$, where $x$ and $y$ are measured in $m$ and $t$ in $s$. The tension is the string is

Assertion: Doppler formula for sound wave is symmetric with respect to the speed of source and speed of observer.
Reason: Motion of source with respect to stationary observer is equivalent to the motion of an observer with respect to stationary source.

The characteristics of a sound with the help of which we can distinguish between shrill note and a grave note is

Two sound waves of wavelengths $2 \mathrm{~m}$ and $2.02 \mathrm{~m}$ produce 15 beats in 3 seconds in a medium. The velocity of sound in that medium is

The phase change between incident and reflected sound wave from a free end is

An open pipe of length $l$ vibrates in fundamental mode. The pressure variation is maximum at

The principle of superposition in wave motion tells that in a motion in which two or more waves are simultaneously producing their displacement in a particle along the same line, then the resultant

Statement-I: A transverse wave is travelling in a string. Equation of the wave is equal of shape of the string at an instant ${t}$.
Statement-II: At a point beats frequency of $n{Hz}$ is observed. It means, at that point, zero intensity is observed $2 {n}$ times per second.

An aluminium rod having a length of $90.0 \mathrm{~cm}$ is clamped at its middle point and is set into longitudinal vibrations by stroking it with a rosined cloth. Assume that the rod vibrates in its fundamental mode of vibration. The density of aluminium is $2600 \mathrm{~kg} \mathrm{~m}^{-3}$ and its Young's modulus is $7.80 \times 10^{10} \mathrm{~N} \mathrm{~m}^{-2}$. Find (a) the speed of sound in aluminium, (b) the wavelength of sound waves produced in the rod, (c) the frequency of the sound produced and (d) the wavelength of the sound produced in air. Take the speed of sound in air to be $340 \mathrm{~ms}^{-1}$.

The intensity ratio of two waves is 1:9. The ratio of their amplitudes, is

Two sitar strings "A" and "B" playing the note "Dha" are slightly out of tune and produce beats of frequency $5 \mathrm{~Hz}$. The tension of the string " $\mathrm{B}$ " slightly increased and the beat frequency is found to decrease to $3 \mathrm{~Hz}$. What is the original frequency of " $\mathrm{B}$ " in hertz, if the frequency of " $\mathrm{A}$ " is $427 \mathrm{~Hz}$ ?

In Quincke's experiment, the sound intensity has a minimum value $I$ at a particular position. As the sliding tube is pulled out by a distance of $16.5 \mathrm{~mm}$, the intensity increases to a maximum of $9 I$. Take the speed of sound in air to be $330 \mathrm{~ms}^{-1}$. (a) Find the frequency of the sound source. (b) Find the ratio of the amplitudes of the two waves arriving at the detector assuming that it does not change much between the positions of minimum intensity and maximum intensity.

A source of sound gives $5$ beats ${\mathrm{s}^{ - 1}}$ when sounded with another source of frequency $100\,\,Hz$. The second harmonic of the source together with a source of frequency $205\,\,Hz$ gives $5\,\,beats\,\,{s^{( - 1)}}$. What is the frequency of the source?

A travelling wave $y=A \sin (k x-\omega t+\theta)$ passes from a heavier string to a lighter string. The reflected wave has amplitude $0.5 \mathrm{~A}$. The junction of the strings is at $x=0$. The equation of the reflected wave is:

For which of the following do the longitudinal waves exist?

Transverse waves can propagate in

The frequency of a note emitted by a source changes by 20% as it approaches an observer. As it recedes away him, the apparent frequency will differ from the actual frequency by

Which of the following properties of a wave does not change with a change in medium?

Two sources $A$ and $B$ are sounding notes of frequency $680 \mathrm{~Hz}$. A listener moves from $A$ to $B$ with a constant velocity $u$. If the speed of sound is $340 \mathrm{~ms}^{-1}$, what must be the value of $u$, so that he hears 10 beats per second?

Two sound waves travel in the same direction in a medium. The amplitude of each wave is $A$ and the phase difference between the two waves is $120^\circ$. The resultant amplitude will

A travelling wave reflected at an open boundary undergoes a phase change of

Statement-I: In stationary wave, all the particles of the medium between two nodes vibrate in same phase with same frequency but with different amplitude.
Statement-II: In stationary wave, every particle of the medium vibrates with its own energy and it does not share or transmit it to any other particle.

The equation of a spherical progressive wave is

A source of sound vibrates according to the equation $y = 0.5\,\,\cos \left( {\pi t} \right).$ If the wave velocity is $1.5\,\,\,{\text{m}}{{\text{s}}^{ - 1}},$ the wave length is

The reason for introducing Laplace correction in the expression for the velocity of sound in a gaseous medium is: