Compression and Rarefaction

Q. The engine of a train sounds a whistle at frequency $\nu$. The frequency heard by a passenger is (If wind is blowing from passenger side to Train side)

1. $\approx \frac{1}{\nu }$
2. $<\nu$
3. $\nu$
4. $>\nu$

Q. An unknown frequency $x$ hertz produces $8$ beats per seconds with a frequency of $250Hz$ and $12$ beats with $270Hz$ source, then $x$ is

Q. The thermodynamic process involved in the propagation of sound wave in gaseous medium is

1. Adiabatic
2. Isothermal
3. Isobaric
4. Isochoric

Q. Among two interfering sources, let sound waves from source $S_1$, be ahead of the phase by ${90}^{\circ }$ relative to that of $S_2$. At an observation point $P$, if $P{S}_1-P{S}_2=1.5\lambda$, then the phase difference between the waves from $S_1$ and $S_2$ reaching $P$ is

1. $3\pi$
2. $\frac{5\pi }{2}$
3. $\frac{7\pi }{2}$
4. $4\pi$

Q. Phase difference between a particle at a compression and a particle at successive rarefaction is

1. $\frac{\pi }{2}$
2. $\frac{\pi }{3}$
3. $\pi$
4. $\frac{\pi }{4}$

Q. A tuning fork A of frequency $510\text{Hz}$ produces $4$ beats per second when sounded with another tuning fork B of unknown frequency. If B is loaded with wax, the number of beats is again $4$ per second. The frequency of the tuning fork B before it was loaded is

1. $510\text{Hz}$
2. $514\text{Hz}$
3. $512\text{Hz}$
4. $506\text{Hz}$

Q. A fork $P$ of unknown frequency gives six beats per second when sounded with another fork $Q$ of frequency $260\text{Hz}$. The fork $P$ is now loaded with a piece of wax and again six beats per second is heard, then frequency of fork $P$ is

1. $260\text{Hz}$
2. $254\text{Hz}$
3. $266\text{Hz}$
4. $250\text{Hz}$

Q. Sound waves in air are always longitudinal because

1. Air have no rigidity
2. Air can be compressed or rarefied
3. Air is a mixture of several gases
4. Air exerts pressure

Q.

Explain how sound waves travel.

Q. A sound wave has a wavelength $\lambda$. The distance between the first compression and the fourth rarefaction is

1. $2.5\lambda$
2. $\lambda$
3. $5\lambda$
4. $3.5\lambda$

Q. The diagram below shows the basic idea behind a disk siren. It consists of a disk in which there are $16$ equally spaced holes, all at the same distance from its axle. When a jet of air is directed at the holes and the disc is rotated at a particular constant rate, the frequency of the note produced is $320Hz$. When a disk containing $24holes$ is rotated at $4/3$ times the rate, then frequency of note produced is $320nHz$ Find the value of $n$.

Q. WHAT IS MATTER WAVES? EXPLAIN IN DETAIL

Q.

What is longitudinal wave motion?

Q. What are the low pressure regions which are created when sound travels through a medium known as?

1. Compression
2. Rarefaction
3. Trough
4. Crest

Q. Consider the following statements about sound passing through a gas
$\left(A\right)$ The pressure of the gas at a point oscillates with time
$\left(B\right)$ The position of a small layer of gas oscillates with time

1. $\left(B\right)$ is correct but $\left(A\right)$ is wrong
2. Both $\left(A\right)$ and $\left(B\right)$ are wrong
3. $\left(A\right)$ is correct but $\left(B\right)$ is wrong
4. Both $\left(A\right)$ and $\left(B\right)$ are correct

Q. An open organ pipe of length 20 cm in its fundamental mode resonates with string clamped at both ends and vibrating in its 2nd overtone. If length of string is 30 cm and velocity of sound is 340 m/s, then speed of travelling wave in string is

1. 680 m/s
2. 340 m/s
3. 170 m/s
4. 226.6 m/s

Q.

Choose the Most appropriate answer.
In a tube when a sound wave is created, compression and rarefaction pulses are produced. The rarefaction pulse has pressure.

1. 0

2. Minimum

3. Negative

4. Minimum but greater than 0

Q. A sound wave is a pressure wave; regions of high (compressions) and low pressure (rarefactions) are established as the result of the vibrations of the sound source. These compressions and rarefactions result because sound :

1. waves have a speed which is dependent only upon the properties of the medium
2. is more dense than air and thus has more inertia, causing the bunching up of sound
3. is able to reflect off fixed ends and interfere with incident waves vibrates longitudinally; the longitudinal movement of air produces pressure fluctuations
4. is like all waves; it is able to bend into the regions of space behind obstacles

Q. Shock waves are produced by objects

1. carrying electric charges and vibrating
2. vibrating with frequency greater than 20000Hz
3. vibrating with very large amplitude
4. moving with a speed greater than that of sound in the medium

Q. When the momentum of a photon is changed by an amount $p^{\prime }$ then the corresponding change in the de-Broglie wavelength is found to be $0.20$%. Then, the original momentum of the photon was

1. $300p^{\prime }$
   
2. $500p^{\prime }$
   
3. $100p^{\prime }$
4. $400p^{\prime }$

Q.

A steel wire has a length of 12.0 m and a mass of 2.10 kg. What should be the tension in the wire so that speed of a transverse wave on the wire equals the speed of sound in dry air at 20 °C = 343 m s^–1.

Q. Consider the following statements about sound passing through a gas
$\left(A\right)$ The pressure of the gas at a point oscillates with time
$\left(B\right)$ The position of a small layer of gas oscillates with time

1. Both $\left(A\right)$ and $\left(B\right)$ are correct
2. $\left(A\right)$ is correct but $\left(B\right)$ is wrong
3. $\left(B\right)$ is correct but $\left(A\right)$ is wrong
4. Both $\left(A\right)$ and $\left(B\right)$ are wrong

Q.

Sound waves are the _________waves.

Q. Assertion :Pressure and density changes do not occur in a transverse stationary wave. Reason: the average distance between any two particles of the wave remains the same.

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
3. Assertion is correct but Reason is incorrect
4. Both Assertion and Reason are incorrect

Q. Pick out the correct statement in the following with reference to stationary wave pattern

1. In a tube closed at one end, all the harmonic are present
2. In a tube open at one end, only even harmonic are present
3. The distance between successive nodes equal to the wavelength
4. In a stretched string, the first overtone is same as the second harmonic
5. Reflection of a wave from a rigid wall change the phase by ${45}^o$

Q. Absorption coefficient can be measured by

1. Microphone
2. Volume resonator
3. Sonometer
4. Megaphone