Tag: reverberation

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Questions Related to reverberation

Multiple choice physics acoustics reverberation applications of reflection of sound multiple reflection of sound and reverberation

RADAR is used for

  1. locating submerged submarines

  2. receiving a signals in a radio receiver

  3. locating geostationary satellites

  4. detecting and locating the position of objects such as aeroplanes
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Radar is an acronym fro RAdio Detection And Ranging

$\rightarrow$ It is basically a detection system that uses radio waves to determine the range, angle or velocity of objects.
$\rightarrow$ More over; used for distance measurement
$\rightarrow$ Hence; can be used for detecting and locating the position of objects like aero planes

Multiple choice physics acoustics reverberation applications of reflection of sound multiple reflection of sound and reverberation

RADAR makes the use of.

  1. Infra-red waves of shorter wavelengths

  2. Radio-waves of very short wavelength

  3. Radio-waves of very long wavelength

  4. Ultraviolet waves of longer wavelengths
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

RADAR systems operate by transmitting radio waves of very short wavelengths (microwaves), which reflect off objects to detect their position and speed.

Multiple choice physics acoustics reverberation applications of reflection of sound multiple reflection of sound and reverberation

A rocket is moving at a speed of $220\,\,m\,\,s^{-1}$ towards a stationary target, emits a sound of frequency  $1000 Hz$. Some of the sound reaching the target gets reflected back to the rocket as echo. The frequency of the echo as detected by the rocket is
(Take velocity of sound $= 330\,\,m\,\,s^{-1}$)

  1. $3500 Hz$
  2. $4000 Hz$
  3. $5000 Hz$
  4. $3000 Hz$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

As the source (i.e rocket) is moving toward the stationary target, therefore the frequency of sound detected by the target is
$\upsilon' = \dfrac{\upsilon _0\nu}{\nu - \nu _s} = \dfrac{1000 \times 330}{330 - 220} = \dfrac{1000 \times 330}{110} = 3000 Hz$
Now the target is the source (as it is the source of echo) and the rocket's detector is the observer who intercepts the echo of frequency \acute{\upsilon}. Hence, the frequency of the echo detected by the rocket is


$\upsilon" = \dfrac{\upsilon'(\nu + \nu _O)}{\nu} = \dfrac{3000(330 + 220)}{330} = 5000 Hz $ 

Multiple choice physics study of sound reverberation applications of reflection of sound applications of ultrasound

State whether given statement is True or False
Sonar make use of ultrasound.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Answer is A.
Ultrasound is sound with a frequency higher than 20 kHz. This is above the human range of hearing. The most common use of ultrasound, creating images, has industrial and medical applications.
Sonar illustrates how a ship on the ocean utilizes the reflecting properties of ultrasound waves to determine the depth of the ocean. A ultrasound wave is transmitted and bounces off the seabed. Because the speed of sound is known and the time lapse between sending and receiving the sound can be measured, the distance from the ship to the bottom of the ocean can be determined. This technique is called sonar (originally an acronym for SOund Navigation And Ranging).

Multiple choice physics study of sound reverberation applications of reflection of sound applications of ultrasound

In SONAR, we use

  1. ultrasonic waves

  2. infrasonic waves

  3. radio waves

  4. audible sound waves
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Answer is A.

Sonar illustrates how a ship on the ocean utilizes the reflecting properties of ultrasound waves to determine the depth of the ocean. A ultrasound wave is transmitted and bounces off the seabed. Because the speed of sound is known and the time lapse between sending and receiving the sound can be measured, the distance from the ship to the bottom of the ocean can be determined. This technique is called sonar (originally an acronym for Sound Navigation And Ranging).

Multiple choice physics study of sound reverberation applications of reflection of sound applications of ultrasound

SONAR is

  1. SOund Navigation And Ranging

  2. SOund Nullyfying And Ranging

  3. SOund Navigation with Amplitude and Ranging

  4. None
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

SONAR is the best example that illustrates how a ship on the ocean utilizes the reflecting properties of sound waves to determine the depth of the ocean. A sound wave is transmitted and bounces off the seabed. Because the speed of sound is known and the time lapse between sending and receiving the sound can be measured, the distance from the ship to the bottom of the ocean can be determined. This technique is called sonar (SOund Navigation And Ranging).

Multiple choice physics study of sound reverberation applications of reflection of sound applications of ultrasound

In a good auditorium the reverberation time is

  1. 0.17 V/A

  2. > 0.17 V/A

  3. < 0.17 V/A

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

The time for which sound continues to be heard (due to persistence) after the source has stopped producing the sound is called reverberation time . Sabine gave a formula for reverberation time of a good building , which is 

               $T=0.16V/A$ ,
where $V=$ volume of building in cubic metre ,
           $A=$ total absorption of building ,
hence option C is correct .

Multiple choice physics study of sound reverberation applications of reflection of sound applications of ultrasound


State whether given statement is True or False
It is usually preferable to have a longer reverberation time in an auditorium for music than one for speeches.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The reverberant sound in an auditorium dies away with time as the sound energy is absorbed by multiple interactions with the surfaces of the room. In a more reflective room, it will take longer for the sound to die away and the room is said to be 'live'. In a very absorbent room, the sound will die away quickly and the room will be described as acoustically 'dead'. But the time for reverberation to completely die away will depend upon how loud the sound was to begin with, and will also depend upon the acuity of the hearing of the observer.
The desirable range of reverberation times for general purpose auditoriums is about 1.5 to 2.5 seconds. Longer reverberation times are sometimes desirable for music and shorter reverberation times are better if the auditorium is to be used for speech only.
Rooms used for speech typically need a shorter reverberation time so that speech can be understood more clearly. If the reflected sound from one syllable is still heard when the next syllable is spoken, it may be difficult to understand what was said. On the other hand the reverberation time is too short, tonal balance and loudness may suffer.
Basic factors that affect a room's reverberation time include the size and shape of the enclosure as well as the materials used in the construction of the room. Every object placed within the enclosure can also affect this reverberation time, including people and their belongings.
Hence, a longer reverberation time is preferred in an auditorium for music than one for speeches.

Multiple choice physics study of sound reverberation applications of reflection of sound applications of ultrasound

Why the ceiling of concert halls, cinema halls made curved?

  1. to make the hall beautiful.

  2. for proper light conditions.

  3. so that the sound can reach all corners properly.

  4. So that the picture or the stage can be visible to each and energy person.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In concert halls, cinema halls, conference halls, the ceiling are made curved, so that the sound after reflection from the curved surface reaches all corners of the hall evenly.