Tag: world of sounds

Questions Related to world of sounds

Time taken to complete a wave is called as

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

  1. Period 

  2. Span

  3. Life 

  4. Duration 

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Correct Option: A
Explanation:

The time taken to complete a wave is termed as period which can be written as $T=\dfrac{1}{f}$ T= time period ; f= frequency 

The wavelength of light absorbed by $Pr$ form of phytochrome is:-

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

  1. $620 nm$

  2. $640 nm$

  3. $680 nm$

  4. $720 nm$

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Correct Option: C
Explanation:

The Pr form absorbs light between $660$ to $680 nm$ and absorbs at a peak of $666 nm$. It is the form synthesized in dark-grown seedlings. When Pr absorbs red light, it is converted to the $Pfr$ form.

Which of the following type of waves is different from others? 

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

  1. Light waves

  2. X-rays

  3. Radio waves

  4. Sound waves

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Correct Option: D
Explanation:

Except sound wave, all other options are electromagnetic waves.

The frequency of a man's voice is $300Hz$ and its wavelength is $1$ meter. If the wavelength of a child's voice is $1.5m$, then the frequency of the child's voice is:

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

  1. $200Hz$

  2. $150Hz$

  3. $400Hz$

  4. $350Hz$

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Correct Option: A
Explanation:

We know that ,

$f=\dfrac{c}{\lambda}$
So,
$\dfrac{f _{man's voice}}{f _{child's voice}}=\dfrac{\dfrac{c}{\lambda _{man's voice}}}{\dfrac{c}{\lambda _{child's voice}}}$
$\dfrac{f _{man's voice}}{f _{child's voice}}$=$\dfrac{\lambda _{child's voice}}{\lambda _{man's voice}}$     
$\dfrac{300}{f _{child's voice}}=\dfrac{1.5}{1}$
$f _{child's voice}=\dfrac{300}{1.5}$
$f _{child's voice}=200 Hz$
  

two waves of same frequency and of intensity ${I} _{0}$ and $9{I} _{0}$ produces interference. If at a certain point the resultant intensity is $7{I} _{0}$ then the minimum phase difference between the two sound waves will be

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

  1. ${90}^{0}$

  2. ${150}^{0}$

  3. ${120}^{0}$

  4. ${100}^{0}$

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Correct Option: C
Explanation:

$\begin{array}{l} 7{ I _{ o } }={ I _{ o } }+a{ I _{ o } }+2\sqrt { { I _{ o } } } \sqrt { x{ I _{ o } } } \cos  \Delta \phi  \ \Rightarrow 7{ I _{ o } }=10{ I _{ o } }+6\cos  \Delta \phi  \ \Rightarrow -3{ I _{ o } }=6\cos  \Delta \phi  \ \cos  \Delta \phi ={ { -1 } }{ 2 } \ \Delta \phi =\dfrac { { 2\pi  } }{ 3 } =\dfrac { { 2\times 180 } }{ 3 } ={ 120^{ 0 } } \ Hence, \ option\, \, C\, \, is\, \, correct\, \, answer. \end{array}$

Sound frequency that can be detected by the human ear is 

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

  1. $1500\ Hz$

  2. $20,000\ Hz$

  3. $12,000\ Hz$

  4. $22,000\ Hz$

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Correct Option: B

When you speak to your friend which of the following quantities have a unique value in the sound produced by both the boys?

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

  1. amplitude

  2. wave velocity

  3. frequency

  4. wavelength

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Correct Option: B
Explanation:

Out of the given quantities , wave velocity has a unique value . Because both the friends are producing the sound in the same medium , and wave velocity depends upon medium , which is not changing here .

Amplitude of the sounds depends upon the energy given by any of the friends to sound , so it may change .
Frequency of sound depends upon the thickness of vocal cords of two friends , so it also may vary . Now wavelength $\lambda \propto 1/f$, for a constant velocity , when frequency $f$ changes , wavelength will also change .

What is the unit of frequency?

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

  1. Hz

  2. Watt

  3. Volt

  4. $m^{-1}$

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Correct Option: A
Explanation:

The unit of frequency is Hz. 

Sound is produced by a

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

  1. vibrating body

  2. moving body

  3. oscillating body

  4. both A and C

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Correct Option: A,B,C
Explanation:

Sound is produced by a vibrating body.
Sound is produced when something vibrates. The vibrating body causes the medium (water, air, etc.) around it to vibrate. Vibrations in air are called travelling longitudinal waves, which we can hear. Sound waves consist of areas of high and low pressure called compressions and rarefactions, respectively.

If one puts one ears to the steel rail, the sound of a coming train can be heard even when the train cannot be seen. One can conclude from this observation that
A. Sound travels faster in steel than in air.
B. Amplitude of sound in the rail is much larger than in air.
C. Sound can travel larger distance in solids than in air.
D. Quality of sound in rail is better than in air.
The reasonable conclusion are

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

  1. A and C

  2. A and B

  3. B and C

  4. None of these

Show answer
Correct Option: B
Explanation:

Velocity of sound is maximum in solids and least in gases
$ V _{gas} < V _{liquid} < V _{solid} $
Intensity would also be much lower in air as $I \propto a^{2}$