Tag: time period, frequency and amplitude of sound

Questions Related to time period, frequency and amplitude of sound

The sound from a mosquito is produced when it vibrates its wings at an average rate of $500$ vibrations per second. What is the time period of the vibration?

physics sound: production of sound oscillation - amplitude, time period and frequency of oscillation time period, frequency and amplitude of sound oscillatory and periodic motion

  1. 0.001

  2. 0.002

  3. 0.003

  4. 0.004

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Correct Option: B
Explanation:

Frequency equals the number of waves that passes a given point per second or the number of oscillations of a vibrating body per second or number of cycles per second.
In this case, a mosquito vibrates its wings at an average rate of 500 vibrations per second. Therefore, the frequency of the sound is 500 Hz.
Time period of the wave is defined as the reciprocal of the frequency of the wave.
That is, $T=\frac { 1 }{ f } =\frac { 1 }{ 500 } =0.002\quad second$.
Hence, time period of the sound produced by the mosquito is 0.002 second.

An object attached to one end of a spring makes 20 vibrations in 10s. Its frequency is

physics sound: production of sound oscillation - amplitude, time period and frequency of oscillation time period, frequency and amplitude of sound oscillatory and periodic motion

  1. 2Hz

  2. 10s

  3. 0.05Hz

  4. 2s

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Correct Option: A
Explanation:

Answer is A.

The frequency (f) of a wave is the number of full wave forms generated per second. This is the same as the number of repetitions per second or the number of oscillations per second.  
In this case, an object attached to one end of a spring makes 20 vibrations in 10 s. That is, 20 vibration in 10 seconds. S in one second it makes 2 vibrations. 
Therefore, the frequency of the object is 2 Hertz.

The number of cycles an oscillator completes in each second is called its _______________.

physics sound: production of sound oscillation - amplitude, time period and frequency of oscillation time period, frequency and amplitude of sound oscillatory and periodic motion

  1. Frequency

  2. Velocity

  3. Amplitude

  4. Angular velocity

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Correct Option: A
Explanation:

The number of cycles an oscillator completes in each second is called its frequency.
The frequency (f) of a wave is the number of full wave forms generated per second. This is the same as the number of repetitions per second or the number of oscillations per second.  

Which is true for a wave ? (here n = frequency, T = time period)

physics sound: production of sound oscillation - amplitude, time period and frequency of oscillation time period, frequency and amplitude of sound oscillatory and periodic motion

  1. nT$=1$

  2. $\displaystyle\frac{n}{T}=2$

  3. n=T

  4. None of these

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Correct Option: A
Explanation:

Frequency is , number of vibrations per (one) second , and time period is the time taken to complete one vibration .

      Let a vibrating body completes n vibrations in 1 s ,
therefore time taken to complete one vibration , $T=(1/n)$ second
  therefore we have , $T=1/n$ ,

            or                  $nT=1$

What is the time period of a wave having frequency of 50 Hz?

physics sound: production of sound oscillation - amplitude, time period and frequency of oscillation time period, frequency and amplitude of sound oscillatory and periodic motion

  1. 0.02 s

  2. 0.20 s

  3. 2.0 s

  4. 20 s

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Correct Option: A
Explanation:

$\text {Time period} = \dfrac{1}{\text{frequency}}= \dfrac{1}{50}=\ 0.02 \ s$

A sound wave completes $24$ cycles in $0.8\;s$. The time period of the wave would be:

physics sound: production of sound oscillation - amplitude, time period and frequency of oscillation time period, frequency and amplitude of sound oscillatory and periodic motion

  1. $1/30\;s$

  2. $30\;s$

  3. $1/24\;s$

  4. $24\;s$

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Correct Option: A
Explanation:

A time period is the time taken to complete one cycle.


Given that, the sound wave completes $24$ cycles in $0.8\,s$

So, the time taken to complete one cycle $=\dfrac{0.8}{24}=\dfrac{1}{30}\,s$

Hence the time period is $\dfrac{1}{30}\,s$

The time period of a vibrating body is $0.01\;sec$. Its frequency will be :

physics sound: production of sound oscillation - amplitude, time period and frequency of oscillation time period, frequency and amplitude of sound oscillatory and periodic motion

  1. $1.0\;s^{-1}$

  2. $10.0\;s^{-1}$

  3. $100.0\;s^{-1}$

  4. $1000.0\;s^{-1}$

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Correct Option: C
Explanation:

Given,


Time period $=0.01\,sec$

We have to find the frequency

We have the relation,

$Frequency=\frac{1}{Time\,Period}$

That is,

$Frequency=\frac{1}{0.01}=100\,s^{-1}$

A man blows a whistle and hears an echo after 1.2 seconds. The distance between the man and the reflector of the sound is _____ m. (take velocity of sound in air as $330 {ms}^{-1}$)

physics sound: production of sound oscillation - amplitude, time period and frequency of oscillation time period, frequency and amplitude of sound oscillatory and periodic motion

  1. 250

  2. 190

  3. 298

  4. 198

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Correct Option: D

A source of sound is moving away from an observer at rest with a velocity $50 {ms}^{-1}$. If the frequency of sound is 200 Hz, find the apparent frequency observed by the observer. (Take velocity of sound = $300 {ms}^{-1}$)

physics sound: production of sound oscillation - amplitude, time period and frequency of oscillation time period, frequency and amplitude of sound oscillatory and periodic motion

  1. 140 Hz

  2. 25.1 Hz

  3. 171.4 Hz

  4. 75.6 Hz

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Correct Option: C

The frequency of sound waves can be expressed in 

physics sound: production of sound oscillation - amplitude, time period and frequency of oscillation time period, frequency and amplitude of sound oscillatory and periodic motion

  1. Hz

  2. $cycle/second$

  3. $s^{-1}$

  4. all the above

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Correct Option: D
Explanation:

The frequency of a wave is the number of waves passing a point in a certain time. The SI unit of frequency is $Hz$. One Hz is equal to one cycle per second.

We also have the relation between the frequency and the time period as:
$f=\frac{1}{T}$
The time is measured in seconds. So the frequency can also be expressed as $s^{-1}$