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 audible, infra and ultra sound with its application study of sound physics

Three different vibrating bodies produce three types of sounds X, Y and Z.
Sounds X and Y cannot be heard by a man having normal range of hearing but sound Z can be heard easily. 
The sound X is used in for monitoring nuclear reactor. The sound similar to that which is produced during an earthquake before the mainshock wave is generated.


What type of sounds are (i) X (ii) Y, and (iii) Z?

  1. X - infrasound, Y - ultrasound, Z - audible sound

  2. X - audible sound, Y - infrasound, Z - ultrasound

  3. X - ultrasound, Y - infrasound, Z - audible sound

  4. X - infrasound, Y - audible sound, Z - audible sound
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Ultrasound is used to see what is happening in a nuclear reactor. Ultrasounds and infrasounds are not audible to man. Ultrasound have frequency more than 20 kHz.
Infrasound have frequency below 20Hz.

Multiple choice audible, infra and ultra sound with its application study of sound physics

If a vibration is produced 200 times per second :

  1. it will be audible by the human ear

  2. it will not be audible by the human ear

  3. it will be audible depending on its amplitude

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

It will be audible by the human ear because vibration is produced 200 times/second. So,frequency =200Hz. And the range of audible frequency is 20Hz-20,000Hz. 

Multiple choice audible, infra and ultra sound with its application study of sound physics

We are able to hear the sounds made by a source if the frequency of sound is:

  1. Within audible range in air

  2. Within audible range in vaccum

  3. Within audible range in water
  4. Within audible range in ${ CO } _{ 2 }$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The human ear can not hear all frequency of sounds. The audible range of the frequency is 20 Hz to 20000 Hz. The human ear is able to hear the sounds those have frequencies in that audible range.   

Multiple choice audible, infra and ultra sound with its application study of sound physics

How are bats able to fly in the dark?

  1. They produce infrasonic waves.

  2. They can hear ultrasonic sounds.

  3. They produce infrared waves.

  4. They can hear infrared waves.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Bats emit ultrasonic sound waves which bounces back from the objects and enables them to sense an obstruction and also hunt for prey.

Multiple choice audible, infra and ultra sound with its application study of sound physics

Which of the following frequency of sound can't be heard by human beings?

  1. 5 Hz

  2. 100 Hz

  3. 500 Hz

  4. 1000 Hz
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The generally accepted standard range of audible frequencies is 20 to 20,000 Hz, although the range of frequencies individuals hear is greatly influenced by environmental factors. Frequencies below 20 Hz are  generally felt rather than heard, assuming the amplitude of the vibration is great  enough. So 5 and 10 Hz both can't be heard by human ear in general.

Multiple choice audible, infra and ultra sound with its application study of sound physics

What is frequency of  the sound of vibrations of pendulum which we can't hear?

  1. below 20 Hz

  2. above 20 Hz

  3. 20 Hz

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

The frequency of a vibrating pendulum is quite small and less than 20 Hz which is not in the audible range. Hence, it is not heard.

Multiple choice audible, infra and ultra sound with its application study of sound physics

Which of the following frequency of sound can't be heard by human beings?

  1. 40 Hz

  2. 400 Hz

  3. 4000 Hz

  4. 40,000 Hz
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The generally accepted standard range of audible frequencies is 20 to 20,000 Hz, although the range of frequencies individuals hear is greatly influenced by environmental factors. Frequencies below 20 Hz are generally felt rather than heard, assuming the amplitude of the vibration is great enough. So sound with frequency 40,000 Hz can't be heard by human ear in general.

Multiple choice audible, infra and ultra sound with its application study of sound physics

We are able to hear the sounds made by a source, if the frequency of sound is :

  1. Within audible range in air

  2. Within audible range in vacuum

  3. Within audible range in water
  4. Within audible range in $CO _2$
Reveal answer Fill a bubble to check yourself
A,C,D Correct answer
Explanation

sound needs a medium to travel and to hear a sound it should be in audible range in any medium.

so the answer is A, C and D.

Multiple choice audible, infra and ultra sound with its application study of sound physics

Which is not the condition for hearing sound?

  1. There must be a vibrating body capable of transferring energy.

  2. There must be a material medium to pick up and propagate energy

  3. The medium must have a large density.

  4. There must be receiver to receive the energy and interpret it.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Dense molecules vibrate at slower speeds. The more dense the string is, the slower it will vibrate, and the lower its frequency will be. Instruments often have strings made of different materials. The strings used for low pitches will be made of a more dense material than the strings used for high pitches. 
The more dense the medium the slower the speed of sound. For example steel is 6000 times more denser than air but 2,000,000 times more elastic than air, so sound travels 16 times faster in steel than in air. 

Multiple choice audible, infra and ultra sound with its application study of sound physics

Which of the following statement is/are true in case of waves ?

  1. Transverse vibrations are set on the string of a guitar.
  2. As compared to light, a sound wave produced on the moon will take a time about $10^6$ times longer to reach the earth.

  3. A sound note of wavelength 1 cm in air cannot be heard by a man.

  4. Sound travels faster in water than in air.
Reveal answer Fill a bubble to check yourself
A,C,D Correct answer
Explanation

(A) When a guitar string is struck , string is disturbed and the medium (string) particles vibrate perpendicular to the direction of motion disturbance , therefore transverse vibrations are set on the guitar string . -True

(B) Sound wave are longitudinal mechanical waves , which require a medium to travel as there is no medium on moon , so they cannot travel there and can't reach to earth . Whereas light waves ,being electromagnetic waves can travel to earth . -False
(C) If wavelength $\lambda=1cm=0.001m$ and $v=332m/s$ ,
then frequency $f=v/\lambda=332/0.001=332000Hz$ ,
that is an ultrasonic frequency which cannot be heard by a man . -True
(D) Sound travels faster in liquid than gases due to higher elasticity of liquids , therefore sound travels faster in water than in air .  -True

Multiple choice audible, infra and ultra sound with its application study of sound physics

Most students have an audible range of about 50Hz to 50kHz.

  1. True

  2. False

  3. Ambiguous

  4. Data insufficient
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Answer is B.

The generally accepted standard range of audible frequencies is 20 to 20,000 Hz, although the range of frequencies individuals hear is greatly influenced by environmental factors. Frequencies below 20 Hz are generally felt rather than heard, assuming the amplitude of the vibration is great enough. Frequencies above 20,000 Hz can sometimes be sensed by young people. High frequencies are the first to be affected by hearing loss due to age and/or prolonged exposure to very loud noises.
Hence, the statement is false.

Multiple choice audible, infra and ultra sound with its application study of sound physics

Three different vibrating objects produce three types of sounds X, Y and Z.
Sounds X and Y cannot be heard by a man having normal range of hearing but sound Z can be heard easily.
The sound X is used in hospital to break kidney stones of a patient into fine grains which then get flushed out with Urine. The sound similar to that which is produced during an earthquake before the main shock wave is generated.

Name one device in our homes which can produce sound like Z.

  1. oven

  2. doorbell

  3. no such device is there in our homes.

  4. all devices produce such sound
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Ultrasound is used for removing kidney stones.

When ultrasound are targeted on such stone,the stones start vibrating at high frequency. The stone due to this vibratory motion. Breakdown into fine particles. Ultrasounds and infrasounds are not audible to man. Ultrasound have frequency more than 20 kHz. A doorbell can produce an audible sound. 
Infrasound have frequency below 20 Hz
X is ultrasound.
Y is infrasound
Z is audible sound.

Multiple choice audible, infra and ultra sound with its application study of sound physics

Three different vibrating objects produce three types of sounds X, Y, and Z. Sounds X and Y cannot be heard by a man having normal a range of hearing but sound Z can be heard easily.  

The sound X is used in a hospital to break kidney stones of a patient into fine grains which then get flushed out with Urine. The sound similar to that which is produced during an earthquake before the main shock wave is generated. What is the frequency range of sounds like Z?

  1. 20 - 20,000 Hz

  2. 20,000-50000Hz

  3. 2-10Hz

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

Ultrasound is used for removing kidney stones.when ultrasound are targeted on such stone,the stones start vubrating at high frequency.the stone due to this vibratory motion. Breakdown into fine particles.ultrasounds and infrasounds are not audible to man.ultrasound have frequency more than 20kHz.



Infrasound have frequency below 20Hz, X is ultrasound. Y is infrasound, Z is audible sound.


Audible sound has frequency between 20Hz -20,000Hz.