Tag: sound

Quizzes (27) Questions (116)

Questions Related to sound

Multiple choice how humans hear sound human ear study of sound sound physics

How does the sound produced by a vibrating object in a medium reach your ear?

  1. Through electron transfer

  2. Through the vibration of particles

  3. Sound waves don't need a medium

  4. Not enough data
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

When an object vibrates, it vibrates the neighbouring particles of the medium. These vibrating particles then vibrate to the adjacent particles. Vibrations in an object create disturbance in the medium and consequently compressions and rarefactions.  In this way, vibrations produced by an object are transferred from one particle to another in the form of compressions and rarefactions till it reaches our ear.
Region of high pressure and high density is called compression and region of low pressure and low density in the air is called rarefaction. As the object continues to vibrate, it produces a series of successive compression and rarefaction in the air, thus, propagating sound through the air and finally reaches our ears.

Multiple choice how humans hear sound human ear study of sound sound physics

The persistence of hearing for human beings is not more than

  1. 1 s
  2. $\displaystyle \frac{1}{5}\:s$
  3. $\displaystyle \frac{1}{10}\:s$
  4. $\displaystyle \frac{1}{2}\:s$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The sensation of hearing of any sound persists in our brain for 0.1s.This is called the persistence of hearing.

so the answer is C.

Multiple choice how humans hear sound human ear study of sound sound physics

Calculate he minimum distance to hear an echo.(taking the velocity of sound in air to be $330 {ms}^{-1}$)

  1. 12.8 m

  2. 24 m

  3. 8.6 m

  4. 17.5 m
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

To hear an echo, sound must travel to the obstacle and back. The minimum time for human ear persistence is 0.1 seconds. Distance = (speed * time) / 2 = (330 * 0.1) / 2 = 16.5 meters. 17.5 meters is the closest provided option.

Multiple choice how humans hear sound human ear study of sound sound physics

When a sound wave enters the ear, it sets the eardrum into oscillation, which  in turn causes oscillation of 3 tiny bones in the middle ear called ossicles. This oscillation is finally transmitted to the fluid filled in inner portion of the ear termed as inner ear, the motion of the fluid disturbs hair calls within the inner ear which transmit nerve impulses to the brain with information that a sound is present. The three bones present in the middle ear are named as hammer, anvil and stirrup. Out of these the stirrup is the smallest one and this only connects the middle  ear to inner ear as shown in the figure below. The area of stirrup and its extent of connection with the inner ear limits the sensitivity of the human ear. Consider a person's eat whose moving part of the eardrum has an area of about 43 mm$^{2}$ and the area of stirrup is about 3.2 mm$^{2}$. The mass of ossicles is negligible. As a result, force  exerted by sound wave in air on eardrum and ossicles is same as the force exerted by ossicles on the inner ear. Consider a sound wave having maximum pressure fluctuation of $3\times10^{-2}$ Pa from its normal equilibrium pressure value which is wqual to $10^{5}$ Pa. Frequency of sound wave is 1200 Hz. 
Data: Velocity of sound wave in air is  332 m/s. Velocity of sound wave in fluid (present in inner ear) is 1500 m/s. Bulk modulus of air is $1.42\times10^{5}$ Pa. Bulk modulus of fluid is $2.18\times10^{9}$ Pa.


Find the pressure amplitude of given sound wave in the fluid of inner ear. 

  1. 0.03 Pa

  2. 0.04 Pa

  3. 0.3 Pa

  4. 0.4 Pa
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Given :   Area of stirrup        $A _s = 3.2 mm^2     = 3.2\times 10^{-6}$ $m^2$

             
  Area of eardrum     $A = 43  mm^2  = 43 \times 10^{-6} m^2$

  Pressure amplitude at eardrum    $P _o =  3 \times 10^{-2}$  Pa

Force exerted by sound wave in air on eardrum       

$F =  P _o A = 3 \times 10^{-2} \times 43 \times 10^{-6}   = 129 \times 10^{-8}$N

According to question , force exerted on eardrum is equal to force exerted by ossicles on the inner ear.

Let pressure amplitude in the fluid of inner ear be  $p' _o$

$\therefore$    $p' _o  = \dfrac{F}{A _s}  =  \dfrac{129 \times10^{-8}}{3.2 \times 10^{-6}}   = 0.4$ Pa

Multiple choice physics sound time period, frequency and amplitude of sound amplitude, time period and frequency of a vibration nature and characteristics of sound waves

Which of the following statements is correct?

  1. Sound travels as waves

  2. Sound travels in straight lines

  3. Sound is a form of energy

  4. All of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Sound travels as mechanical waves. A mechanical wave is a disturbance that moves and transports energy from one place to another through a medium. In sound, the disturbance is a vibrating object. And the medium can be any series of interconnected and interactive particles. This means that sound can travel through gases, liquids and solids.

Solution A: Sound travels as waves.

Multiple choice physics sound time period, frequency and amplitude of sound amplitude, time period and frequency of a vibration nature and characteristics of sound waves

A sound is produced by plucking a string in a musical instrument, then

  1. the velocity of wave in the string in equal to the velocity of sound in the string.

  2. the frequency of the wave in the string in equal to the frequency of the sound produced.

  3. the wave in the string is progressive.

  4. the tension in string varies from point to point.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Frequency of the wave is the property which depends on source.

Multiple choice physics sound time period, frequency and amplitude of sound amplitude, time period and frequency of a vibration nature and characteristics of sound waves

If A is the amplitude of vibration, then the time taken by a wave to cover a distance of 4A is known as

  1. Time period

  2. Half the time period

  3. 1 s

  4. 0.1 s
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Time required to complete one vibration is T secs

In one full vibration, the particle covers a total distance of 4A

Thus, time required to cover a total distance of 4A during one vibration is T secs or 1 Time period

The correct option is (a)

Multiple choice physics sound time period, frequency and amplitude of sound amplitude, time period and frequency of a vibration nature and characteristics of sound waves

A sound wave travels with a speed of 330 m s$^{-1}$ in air. If the wavelength of the wave is 110 cm, then frequency of the wave is _______.

  1. 100 Hz

  2. 200 Hz

  3. 300 Hz

  4. 400 Hz
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Using the formula v = f * lambda, where v = 330 m/s and lambda = 110 cm = 1.1 m. Thus, f = v / lambda = 330 / 1.1 = 300 Hz.