Tag: physics

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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. 

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

Human ears can sense sound waves travelling in air having wavelength of ________.

  1. ${10}^{-3}m$
  2. ${10}^{-2}m$
  3. $1 m$
  4. ${10}^{2}m$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Human ears can sense sound waves travelling in air whose frequencies $f$ lie in the range of $20Hz$ to $20kHz$

The average speed $v$ of sound in air is $335m/s$
Wavelength $\lambda=\cfrac vf$
Hence the wavelength range of audible sounds is $\cfrac{335}{20000}$  $to$  $\cfrac{335}{20}$
That is $1.675\times{10^{-2}}$ metres to $16.75$ metres
You can see that among all the 4 options given, only $1m$ fits in the audible range.

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

Voices of men, Women and children different because of

  1. The pitch

  2. The length and the thickness of vocal cords.

  3. Both

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

The voices of men, women and children differ from each other
due to the following factors:

i) The pitch is one of the most essential factors to determine the voice of the individual. For example, men have lower-pitched voices while women have higher-pitched voices.

(ii) Second factor which brings in the difference in the voices is the length and the thickness of vocal cords.  from each other due to the following factors

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

 State True or False.

All inaudible sounds produces frequencies less than 20 Hz.

  1. True

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

The frequency range of audible sound is $20 Hz$ to $20000 Hz$. Thus, the sound below the frequency 20 Hz is inaudible for human ear and the sound above the frequency 20000 Hz is inaudible for human ear. Thus, the given statement is false. 

Multiple choice physics measurements and units some examples of derived units fundamental and derived quantities fundamental and derived units

The unit of power is:

  1. $Kilowatt$
  2. $kWhv$
  3. $dyne$
  4. $joule$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Power is defined as the work done per unit time. So to get the SI unit of power :

$Power=\dfrac{Work}{Time}$

SI unit of Work $=$ Joules

SI unit of Time $=$ second

So S.I. unit of power $=\dfrac{Joule}{Second}=Watt$

$1000\,Watt=1\,Kilowatt$

Multiple choice physics measurements and units some examples of derived units fundamental and derived quantities fundamental and derived units

The velocity of a particle is given as $v = a + b t + c t ^ { 2 }$ .the velocity is measured in $\mathrm { ms } ^ { - 1 }$ , then units of a and c are

  1. $m s ^ { - 1 } \text { and } m s ^ { - 3 }$
  2. $m s ^ { - 2 } \text { and } m s$
  3. $m ^ { 2 } s \text { and } m s ^ { 2 }$
  4. $m s \text { and } m s ^ { - 1 }$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The magnitudes of physical quantities can be added together or subtracted from one another only if they have the same dimensions. 

$[a]=[u]=ms^{-1}$

$[ct^2]=[v]=ms^{-1}$

$[c]=[\dfrac{v}{s^2}]=ms^{-1-2}$

$[c]=ms^{-3}$
Option A