Tag: audible, infrasonic and ultrasonic sounds

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Questions Related to audible, infrasonic and ultrasonic sounds

Multiple choice physics range of hearing sound: production of sound audible, infrasonic and ultrasonic sounds different sounds

A man fires a gun and hears the echo after $2\,\frac{1}{2}sec$. If the velocity of sound in air is $340ms^{-1}$ his distance from the cliff causing the echo is 

  1. $2\,\frac{1}{2}km$

  2. $425m$

  3. $850m$

  4. $136m$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Total distance traveled by sound is 2 * d = v * t. d = (v * t) / 2 = (340 * 2.5) / 2 = 340 * 1.25 = 425 m.

Multiple choice physics range of hearing sound: production of sound audible, infrasonic and ultrasonic sounds different sounds

A sound wave of pressure amplitude $5$ pascal propagates through the air medium. The normal pressure of air is $1.0\times10^5 N/m^2$. The difference between maximum and minimum pressure in the medium is 

  1. $5\times10^5 N/m^2$

  2. $10\times10^5 N/m^2$

  3. $10 N/m^2$

  4. $None\ of\ these$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The pressure amplitude is the difference between the maximum pressure and the ambient pressure. The difference between maximum and minimum pressure is twice the pressure amplitude: 2 * 5 = 10 N/m^2.

Multiple choice physics range of hearing sound: production of sound audible, infrasonic and ultrasonic sounds different sounds

A siren emitting a sound of frequency $1000 Hz$ moves away from you towards a cliff at a speed of $10 m/s$ [speed of sound in air $330 m/s$] Then. 

  1. The frequency of the sound you hearing coming directly from the siren is $ \dfrac {33}{34} \times 1000 Hz $.

  2. The frequency of the sound you hearing coming directly from the siren is $ \dfrac {33}{32} \times 1000 Hz $.

  3. The frequency of the sound you hear reflect off the cliff $ \dfrac {33}{32} \times 1000 Hz $.

  4. The frequency of the sound you hear reflect off the cliff $ \dfrac {33}{34} \times 1000 Hz $.
Reveal answer Fill a bubble to check yourself
C Correct answer
Multiple choice physics range of hearing sound: production of sound audible, infrasonic and ultrasonic sounds different sounds

A person moving in a car with a velocity of $36kmph $ towards a fort wall blows a horn. If he hears the echo after $3s$, the distance of the wall from him. when he blows then horn (velocity of sound $340ms^P{-1}$)

  1. $340m$

  2. $1050m$

  3. $700m$

  4. $525m$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The sound travels to the wall and back. Let d be the distance when the horn is blown. The wall is stationary. The sound travels distance d + (d - v_car * t) = 2d - v_car * t. 2d - v_car * t = v_sound * t. 2d = (v_sound + v_car) * t. v_car = 36 km/h = 10 m/s. 2d = (340 + 10) * 3 = 350 * 3 = 1050. d = 525 m.

Multiple choice physics range of hearing sound: production of sound audible, infrasonic and ultrasonic sounds different sounds

Bats detect the obstacles in their path by receiving the reflected

  1. infrasonic waves

  2. ultrasonic waves

  3. micro waves

  4. radio waves
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Answer is B.

Most bats produce echolocation sounds by contracting their larynx (voice box). A few species, though, click their tongues. These sounds are generally emitted through the mouth. Echolocation calls are usually ultrasonic, ranging in frequency from 20 to 200 kilohertz (kHz), whereas human hearing normally tops out at around 20 kHz.
While using echolocation, the bats emit a series of short, high-frequency sounds from their mouths or nostrils that bounce off objects and surfaces and then return to the animals ears. Since high-frequency waves do not diffract, or bend, extensively, these ultrasonic vibrations provide bats with accurate maps of their surroundings. 

Multiple choice physics range of hearing sound: production of sound audible, infrasonic and ultrasonic sounds different sounds

Echocardiography is used to diagnose heart diseases which utilises infrasonic waves.

  1. True

  2. False

  3. Ambiguous

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

An echocardiogram (also called an echo) is a type of ultrasound test that uses high-pitched sound waves that are sent through a device called a transducer. The device picks up echoes of the sound waves as they bounce off the different parts of your heart. These echoes are turned into moving pictures of your heart that can be seen on a video screen.
Hence, the statement is false.

Multiple choice physics range of hearing sound: production of sound audible, infrasonic and ultrasonic sounds different sounds

Sound of frequency below $20 \ Hz$ is called

  1. audio sounds

  2. infrasonic

  3. ultrasonic

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

Sound waves are categorized on the basis of their frequency range.

Sound of frequency below $20 \ Hz$ is called as infrasonic. Sound of frequency above $20 \ kHz$ is called as ultrasonic whereas sound of frequency in between $20 \ Hz$ to $20 \ kHz$ is called as audio sound.

Multiple choice physics sound audible, infrasonic and ultrasonic sounds different sounds range of hearing

The sounds having frequency less than 20 Hz are called ultrasonics.

  1. True

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

Human beings can normally hear sounds with a frequency between about 20 Hz and 20,000 Hz. Sounds with frequencies below 20 hertz are called infrasound. Infrasound is too low-pitched for humans to hear.

so the answer is B.