Physics · Science General

Acoustics and Sound Waves

2,160 Questions

Acoustics and sound waves deal with mechanical vibrations traveling through media like air and water. Key concepts include wave reflection, beats, echoes, the Mach number, and infrasound. These physics fundamentals are regularly tested in general science sections of multiple competitive exams.

Sound wave propagationEchoes and reflectionWave interferenceMach numberInfrasound frequency

Acoustics and Sound Waves Questions

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

Identify the device which work on the reflection of sound.

  1. Megaphone

  2. Stethoscope

  3. Sound boards

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Megaphone, Stethoscope and Sound boards work on the reflection of sound.

$1.$Megaphone is a portable, cone shaped acoustic horn used to amplify a person's voice or other sounds and direct it in a given direction.
$2.$Stethoscope is an acoustic medical device for listening to the internal sounds of an animal or human body.
$3.$Sound board is the surface of a string instrument that the string vibrate against.

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

Which of the following are examples of multiple reflections of sound?

  1. Stethoscope

  2. Sound board

  3. Megaphone

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Process in which sound waves bounces off obstacles and reflects many times before reaching destinations is known as multiple reflection of sound, So, all of the above are examples of multiple reflections of sound

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

What is multiple reflection of sound?

  1. Process in which sound waves bounces off obstacles and reflects many times before reaching destinations

  2. Process in which sound waves penetrates in obstacles and reflects many times before reaching destinations

  3. Process in which sound waves bounces off obstacles and deflects one time before reaching destinations

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

Process in which sound waves bounces off obstacles and reflects many times before reaching destinations is known as multiple reflection of sound

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

The persistence of audible sound due to the successive reflections from the surrounding objects even after the source has stopped to produce that sound is called _________.

  1. reflection

  2. echo

  3. reverberation

  4. rarefaction
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In big rooms or halls,echos (due to multiple reflection of sound from the walls, roof, floor) follow so closely behind the original sound that the original sound appears to be prolonged even when the source of sound stops producing sound.

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

Why do distant sounds such as those of traffic and loudspeakers become louder during the night time than during the day time?

  1. Due to the reflection of sound waves.

  2. Due to the refraction of sound waves.

  3. Due to the absence of other sounds.

  4. Due to a clear perception of hearing.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Sound waves travel differently at night than during the day. During the day, the sound bends away from the ground;during the night, it bends towards the ground. 

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

In an unoccupied hall of a choultry you will experience the echo effect of sound. If the same hall is furnished with almirahs, tables, chairs,and other commodities, you may not experience the echo clearly. It is because, 

  1. Sound waves get absorbed by the objects in the hall.

  2. The area of reflecting surface decreases.

  3. Reflected sound is reflected again.

  4. Sound does not get reflected again.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

echo is heard due to reflection of sound and if obstacles are placed in path of sound then they will either absorb sound or will not perfectly reflect sound as before so echo will be not effective one .

so the answer is A.

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

The persistence of sound in a closed enclosure, due to continuous reflections at the walls, even after the source has stopped producing sound is known as

  1. The persistence of hearing

  2. An echo

  3. Reverberation

  4. The ultra sounds
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Reverberation is the phenomenon of persistence of sound in a closed enclosure, due to multiple reflection of sound from the walls, even after the source has stopped producing sound. The intensity of sound gets reduced after each reflection.

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

Perforated card boards are used in halls, for

  1. reflection of sound

  2. absorption of sound

  3. refraction of sound

  4. as a decorative material
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Perforated card boards are used for the absorption of sound, as they are good sound absorbents and decrease reverberation time. 

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

For good absorption of sound in auditorium it requires

  1. a few windows to be opened

  2. all closed windows

  3. maps hanging from walls

  4. hanging light curtains.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A few window should be kept opened for the good absorption of sound in auditorium. Because if we open few windows, more sound will absorbed and more will be the sound clarity and better sound effect can be experienced. 

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

In an auditorium the big curtain when falls suddenly then the reverberation time

  1. increases

  2. decreases

  3. Remains same

  4. becomes zero
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The reverberation time will get decreased because curtain will abrosh the sound and more sound will get abrashed then the earlier.  

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

The total absorption of a volume $12000 m^3$ is equal to $1000 m^2$ in the units of an open window. Total absorption of the hall is increased to $2000m^2$ due to entry of audience. The change in its reverberating time is

  1. $1s$
  2. $2s$
  3. $3s$
  4. $4s$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Reverberation time (T) is given by T = 0.161 * V / A. Initially, T1 = 0.161 * 12000 / 1000 = 1.932s. After adding audience, A2 = 2000, so T2 = 0.161 * 12000 / 2000 = 0.966s. The change is approximately 1s.

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

In theatres, big halls., the reverberation of sound is a common problem.

  1. True

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

since the halls and theatres are big enough so that we can distinguish between the generated sound and the reflected sound so the reverbereation  easily happens .

so the answer is A.

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

A meeting hall of volume $100\times30\times10 m^3$ has a reverberation time of 3 seconds. If 1000 visitors are in the hall. The absorption of total visitors if the sound absorption of each visitor is 0.5 is:

  1. 500metric sabin

  2. 600metric sabin

  3. 700metric sabin

  4. 800metric sabin
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

absorption of each visitor is 0.5
so, absorption for 1000 visitor is $1000\times 0.5$
$=500 metric sabine$