Tag: sound waves are longitudinal waves

Questions Related to sound waves are longitudinal waves

The velocity of sound in air is not affected by change in 

physics world of sounds characteristics of sound wave time period, frequency and amplitude of sound sound waves are longitudinal waves

  1. the moisture content of the air.

  2. the temperature of air.

  3. the atmospheric pressure.

  4. the composition of air.

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Correct Option: C
Explanation:

The speed of sound depends on temperature. The formula relating speed of sound and temperature is as follows:

$v = 331 + 0.6 \times T$, where $T$ is temperature in absolute scale and $v$ is in $m/s$.
Humidity has little effect on the speed of sound.
Air pressure has no effect at all in an ideal gas approximation. This is because pressure and density both contribute to sound velocity equally, and in an ideal gas the two effects cancel out each other, leaving only the effect of temperature.
Composition of air has also almost no effect on the speed of sound.

Consider the following
l. Waves created on the surfaces of a water pond by a vibrating source.
ll. Wave created by an oscillating electric field in air.
lll. Sound waves travelling under water. 
Which of these can be polarized

physics world of sounds characteristics of sound wave time period, frequency and amplitude of sound sound waves are longitudinal waves

  1. l and ll

  2. ll only

  3. ll and lll

  4. l, ll, and lll

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Correct Option: A
Explanation:

Sound waves are longitude and can not be polarized. Answer A

The longitudinal wave can be observed in

physics study of sound types of waves sound as a wave of disturbance sound waves are longitudinal waves

  1. Elastic media

  2. inelastic media

  3. Both $(1)$ & $(2)$

  4. None of these

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Correct Option: A
Explanation:

Longitudinal waves travel only in the elastic medium. These waves comprise of compressions and rarefactions. The speed of Longitudinal waves is given by :

$v=\dfrac{\sqrt{B}}{\rho }$ where B is the bulk modulus of elasticity and $\rho $ is the density of the medium

A transverse wave along a string is given by y=$2\sin \left( {2\pi \left( {3t - x} \right) - \frac{\pi }{6}} \right)$, where x and y are in cm and 't' is in second. The acceleration of a particle located at x=4cm at t =1s is 

physics study of sound types of waves sound as a wave of disturbance sound waves are longitudinal waves

  1. $36\pi ^2$

  2. $72\pi ^2$

  3. $18\pi ^2$

  4. $12\pi ^2$

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Correct Option: A

The waves propagating on water surface are

physics study of sound types of waves sound as a wave of disturbance sound waves are longitudinal waves

  1. ultrasonic

  2. longitudinal

  3. unaudible

  4. transverse

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Correct Option: B,D
Explanation:

The answers are (B) and (D).

The waves on the surface of the water are neither longitudinal nor transverse.The wave on the water surface is the superposition of transverse and longitudinal motions of the molecules.

The property of a medium necessary for wave propagation is its

physics study of sound types of waves sound as a wave of disturbance sound waves are longitudinal waves

  1. elasticity

  2. low resistance

  3. inertia

  4. all of the above

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Correct Option: D
Explanation:

The properties of a medium necessary for wave propagation are its elasticity, low resistance and inertia. 
Ans: D

When a stone is dropped on the surface of still water, the waves produced are 

physics study of sound types of waves sound as a wave of disturbance sound waves are longitudinal waves

  1. stationary

  2. transverse

  3. longitudinal

  4. none of the above

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Correct Option: B
Explanation:

On the surface of water transverse waves form.
Option "B" is correct.

When a sound wave goes from one medium to another , the quantity that remains unchanged is

physics study of sound types of waves sound as a wave of disturbance sound waves are longitudinal waves

  1. Frequency

  2. amplitude

  3. wavelength

  4. speed

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Correct Option: A
Explanation:

The electric and magnetic fields have to remain continuous at the refractive index boundary. If the frequency changed, the light at each side of the boundary would be continuously changing it's relative phase and there would be no way to match the fields.
Furthermore, for conservation of energy frequency should remain same.
Energy $E' = h\nu'$ inside the glass must be equal to the energy outside, so
$E = E'$ gives
$h\nu = h\nu'$
so $\nu = \nu'$
the frequency in the medium is equal to that of outside.
Ans: A

Waves inside a gas are

physics study of sound types of waves sound as a wave of disturbance sound waves are longitudinal waves

  1. Longitudinal

  2. Transverse

  3. Partly longitudinal, partly transverse

  4. None of these

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Correct Option: A
Explanation:

When a wave propagates through a gas, the displacement of the particle is parallel to wave propagation. Thus, it's a longitudinal wave. 

State whether the given statement is True or False :
Sound waves are transverse whereas light waves are longitudinal in nature in air.
physics study of sound types of waves sound as a wave of disturbance sound waves are longitudinal waves

  1. True

  2. False

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Correct Option: B
Explanation:

Sound is a mechanical wave that results from the back and forth vibration of the particles of the medium through which the sound wave is moving. If a sound wave is moving from left to right through air, then particles of air will be displaced both rightward and leftward as the energy of the sound wave passes through it. The motion of the particles is parallel to the direction of the energy transport. This is what characterizes sound waves in air as longitudinal waves.
Hence, the statement is false.