Tag: audible, infrasonic and ultrasonic sounds

Quizzes (0) Questions (35)

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

The property of ultrasonic waves used in manufacturing emulsion for photographic films is its, _____________

  1. High speed

  2. High frequency

  3. Higher wavelength

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

The property of ultrasonic waves in manufacturing emulsion for photographic films in its high frequency. The frequency of ultrasonic wave is above $20 KHz$

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

The grandparents and parents of two-year old girl are playing with her in a room. A sound source produces a $28 kHz$ sound. Who in the room is most likely to hear the sound?

  1. Grandparent

  2. Little girl

  3. Both

  4. None of them
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
The frequency range of hearing in infants is more than in adult. As the infant gets mature, this range decreases. So two year girl will be more likely to hear that sound.
So the answer is B.
Multiple choice physics range of hearing sound: production of sound audible, infrasonic and ultrasonic sounds different sounds

The sound intensity is 0.008 $W/m^2$ at a distance of 10 m from an isotropic point source of power of the source is approximately :

  1. 2.5 watt

  2. 0.8 watt

  3. 8 watt

  4. 10 watt
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Intensity I = P / (4 * pi * r^2). Given I = 0.008 and r = 10, P = I * 4 * pi * r^2 = 0.008 * 4 * 3.14 * 100 = 0.008 * 1256 = 10.048 watts, which is approximately 10 watts.

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

A train running at 108 km/hr towards east whistles at a frequency of 800 Hz. The frequencies heard by a passenger sitting in the train and a person standing near the track whom the train has just passed (Speed of Sound = 330 m/s) 

  1. 800 Hz, 733 Hz

  2. 740 Hz, 800 Hz

  3. 800 Hz, 880 Hz

  4. 800 Hz, 750 Hz
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

For a passenger sitting inside the train, there is no relative motion, so the frequency heard remains the source frequency of 800 Hz. For a person standing near the track whom the train has just passed, the train is moving away, so the observed frequency is f' = f * (v / (v + v_s)) = 800 * (330 / (330 + 30)) = 733 Hz.

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

The driver of a car travelling at the speed of $30m/sec$ towards a hill sounds a horn of frequency $600\ Hz$. If the velocity of sound in air is $330m/s$, the frequency of reflected sound as heard by the driver is

  1. $500\ Hz$
  2. $550\ Hz$
  3. $555.5\ Hz$
  4. $720\ Hz$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The frequency heard by the hill is f' = f * (v / (v - vs)) = 600 * (330 / (330 - 30)) = 600 * (330 / 300) = 660 Hz. This reflected sound acts as a source moving towards the driver, so f'' = f' * ((v + vo) / v) = 660 * ((330 + 30) / 330) = 660 * (360 / 330) = 720 Hz.

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

Ultrasonic, intrasonic and audible waves travel through a medium with speeds $V _u,V _i,$ and $V _a$ respectively, then (given constant temperature)

  1. $V _i=V _a=V _u$
  2. $V _u>V _a>V _i$
  3. $V _u < V _a < V _i $
  4. ${ V } _{ a }\le { V } _{ u }={ V } _{ i }$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The speed of sound in a medium depends on the properties of the medium (density, elasticity) and temperature, not on the frequency of the sound wave.