Tag: sound as a wave of disturbance

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Multiple choice physics superposition of waves-1: interference and beats sound as a wave of disturbance vibrations in a tuning fork vibrations in tuning fork

Two sound waves of wavelengths $1\space m$ and $1.01\space m$ produce $10$ beats in $3$ seconds. Then, the velocity of the sound is

  1. $330\space ms^{-1}$
  2. $333.3\space ms^{-1}$
  3. $336.7\space ms^{-1}$

  4. none of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

From the formula, $v=f \lambda$

and the velocity of the sound in air is frequency independent.

for two frequencies $f _1$ and $f _2$, wavelengths are $\lambda _1$ 

and $\lambda _2$ , then the beats will be

$f _1-f _2=v\left(\dfrac{1}{\lambda _1}-\dfrac{1}{\lambda _2}\right)=v\left(\dfrac{\lambda _2-\lambda _1}{\lambda _2  \lambda _1}\right)$

$\dfrac{10}{3}=v\left(\dfrac{0.01}{1.0\times 1.01}\right)$

$v=\dfrac{10\times 1.0\times 1.01}{3.0\times 0.01}=336.66\ \text{ms}^{-1}$

Option "C" is correct.

Multiple choice physics study of sound sound as a wave of disturbance vibrations in a tuning fork vibrations in tuning fork

A _________________ wave has oscillations in the same direction as its motion.

  1. Longitudinal

  2. Oscillatory

  3. Vibrational

  4. matter
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A longitudinal wave has oscillations in the same direction as its motion.
Longitudinal waves, also known as l-waves, are waves in which the displacement of the medium is in the same direction as the direction of travel of the wave. Longitudinal waves are also called compressional waves or compression waves, because they produce compression and rarefaction when traveling through a medium.  In longitudinal waves, the displacement of the medium is parallel to the propagation of the wave. 

Multiple choice physics study of sound sound as a wave of disturbance vibrations in a tuning fork vibrations in tuning fork

The sound propagates in a gaseous medium as :

  1. transverse waves

  2. longitudinal waves

  3. both (a) and (b)

  4. neither (a) nor (b)
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Sound is a sequence of waves of pressure which propagates through compressible media such as air or water. Sound propagates as longitudinal waves in gaseous medium. Longitudinal waves are the waves in which the displacement of the medium is in the same direction, or the opposite direction to the direction to the direction of propagation of wave.

Multiple choice physics study of sound sound as a wave of disturbance vibrations in a tuning fork vibrations in tuning fork

Match the columns

i) particles of medium move parallel to the propagation of disturbance. a) Transverse wars
ii) particles of medium oscillate up and down about their mean position. b) longitudual wars.
iii) particles of the medium oscillate oscillate back and forth about their position of vest.
iv) particles move about their mean positions in a direction perpendicular to the direction of waves propagation

  1. a - i, ii, b - iii, iv

  2. a - i, iii, b - ii, iv

  3. a - iii, iv, b - i, ii

  4. a - iv, ii, b - i, iii
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

In a wave if the particles of medium , vibrate perpendicular to the direction of wave motion (disturbance) then this wave is called a longitudinal wave .

 If the particles of medium , vibrate parallel to the direction of wave motion (disturbance) then this wave is called a transverse wave .
According to these definitions , we can match the given columns as :
a-iv ,ii and b-i,iii . 

Multiple choice physics study of sound sound as a wave of disturbance vibrations in a tuning fork vibrations in tuning fork

Fix up one end of a slinky to a hook and hold it horizontally. Vibrate the other end to and fro along the length of the spring. If you look the spring carefully , you will see some parts of the spring are pushed closer , while some other parts are pulled apart.

  1. The portions which are pushed closer are called compressions

  2. The portions which are pulled apart are called rarefactions

  3. Both A and B are correct

  4. Neither of A and B is correct
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Compressions are the regions of high density and rarefactions are regions of low density.These compressions and rarefactions result because sound is able to reflect off fixed ends and interfere with incident waves vibrates longitudinally; the longitudinal movement of air produces pressure fluctuations. 

Multiple choice physics study of sound sound as a wave of disturbance vibrations in a tuning fork vibrations in tuning fork

Which of the following are true.

  1. the sound and light waves both are longitudinal waves

  2. both the sound and light waves are transverse

  3. in air ,the sound waves are longitudinal as well as transverse

  4. in air, the sound waves are longitudinal and the light waves are transverse
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Longitudinal waves are always characterized by particle motion being parallel to wave motion. A sound wave travelling through air is a classic example of a longitudinal wave. Transverse wave moves perpendicular to the direction of wave motion. Light waves are transverse in nature.