Tag: comparison of speed of sound with speed of light

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Questions Related to comparison of speed of sound with speed of light

Multiple choice physics propagation of sound waves longitudinal vs transverse wave sound and light comparison of speed of sound with speed of light

The frequency of fundamental mode of vibration of an air column enclosed in a closed end pipe is 250 Hz. If its length is 33 cm, then find the velocity of sound in air.

  1. $390 {ms}^{-1}$

  2. $160 {ms}^{-1}$

  3. $330 {ms}^{-1}$

  4. $150 {ms}^{-1}$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

For a closed pipe, the fundamental frequency f = v / (4 * L). Given f = 250 Hz and L = 33 cm = 0.33 m, v = f * 4 * L = 250 * 4 * 0.33 = 1000 * 0.33 = 330 m/s.

Multiple choice physics propagation of sound waves longitudinal vs transverse wave sound and light comparison of speed of sound with speed of light

A wave has a frequency of $5$ GHz.
What is the period of the wave?

  1. $200$ ps

  2. $0.2$ ns

  3. $20$ ns

  4. $20000$ $\mu s$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Given that,


Frequency $f=5 GHz=5\times10^{9}\ Hz$


The period of the wave is reciprocal of frequency.

$T=\dfrac{1}{f}$

$T=\dfrac{1}{5\times10^{9}}$

$T=2\times10^{-10}$

$T=0.2\ ns$

The period of the wave is $0.2\ ns$

Hence, B is correct option.

Multiple choice physics propagation of sound waves longitudinal vs transverse wave sound and light comparison of speed of sound with speed of light

Which of the following product of $e, h, \mu, G$ (where $\mu$ is the permeability) be taken so that the dimensions of the product are same as that of the speed of light?

  1. $h e^{-2} \mu^{-1} G^0$

  2. $h^2 e G^0 \mu$

  3. $h^0 e^2 G^{-1} \mu$

  4. $h G e^{-2} \mu^{0}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The speed of light c has dimensions [LT^-1]. Using the relation c = 1/sqrt(mu_0 * epsilon_0), and checking dimensions of h, e, G, mu, the combination h * e^-2 * mu^-1 yields the correct dimensions of velocity.

Multiple choice physics propagation of sound waves longitudinal vs transverse wave sound and light comparison of speed of sound with speed of light

The ratio of speed of ultrasonic wave and sound wave is:

  1. $=1$

  2. $>1$

  3. $<1$

  4. $>1$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Ultrasonic wave is  defined as “inaudible sound with high frequency for human” the frequency of which generally exceeds 20 kHz. These days, sound wave which is not intended to be heard is also called Ultrasonic wave .


Ultrasonic wave is also a type of sound wave so ratio of velocity is $=1$

Multiple choice physics propagation of sound waves longitudinal vs transverse wave sound and light comparison of speed of sound with speed of light

A laser signal sent towards the moon returns after T seconds.If c is the speed of light, then  the distance of the moon from the observer is given by

  1. cT

  2. $c{T^{ - 2}}$

  3. $\frac{{ct}}{2}$

  4. 2 cT
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The total distance traveled by the signal is 2 * distance (to and back). Since distance = speed * time, 2 * d = c * T, therefore d = c * T / 2.

Multiple choice physics propagation of sound waves longitudinal vs transverse wave sound and light comparison of speed of sound with speed of light

The speed of sound is $330 ms^{-1}$ and that of light is $3\times 10^8 ms^{-1}$. The ratio of speed of sound to that of light is approximately $1 : 10^6$.

  1. True

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

Speed Of Sound$(V)$  is,  $330m/s$  and  that of Light$(U)$  is,  $300*10^{6}m/s$

Now we have to find,  $V:U$  and i.e.,  $V:U=330:300*10^{6}\cong1:10^{6}$ , because in comparison to $U$(Speed of Light)  ,  Speed of Sound$(V)$  is comparetively very $small$.
So, we can assume that, Speed of Sound$(V)$  is $300m/s$  in comparison to that of Speed of Light$(U)$ that is  $3*10^{6}$
Hence,  $V:U=1:10^{6}$

Hence, it is True.
Option A is correct

Multiple choice physics propagation of sound waves longitudinal vs transverse wave sound and light comparison of speed of sound with speed of light

If you hear a gun shot 1 seconds after it is fired, how far away from the gun are you? (speed of sound in air $=330 ms^{-1})$

  1. <span>230 m</span>

  2. <span>330 m</span>

  3. <span>430 m</span>

  4. <span>530 m</span>
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Here we use the concept of Distance formula i.e.,  $d=vt$ , where  $d$  is the distance travelled,  $v$  is the speed and $t$  is the time taken.

Now, According to question;
Given;  $t=1s$  and  $v=330m/s$,
have to find  $d$  and that is,  $d=vt=330*1=330m$

Hence, option  B  is correct.

Multiple choice physics propagation of sound waves longitudinal vs transverse wave sound and light comparison of speed of sound with speed of light

Light .......... travel in vacuum , but the sound ........ travel in vacuum.

  1. Cannot , can

  2. Can, cannot

  3. Sometimes, never

  4. Never, sometimes
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The light can travel in vacuum, but the sound can not travel in vacuum. speed of light in air is $\displaystyle 3\times { 10 }^{ 8 }{ m }/{ s }$

Multiple choice physics propagation of sound waves longitudinal vs transverse wave sound and light comparison of speed of sound with speed of light

Speed of light in air is about ....... times greater than the speed of sound in air.

  1. Million

  2. Trillion

  3. Billion

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

The speed of light in air is $\displaystyle 3\times { 10 }^{ 8 }{ m }/{ s }$ which is about a million times greater than the speed of sound in air (i.e. 330 m/s at $\displaystyle { 0 }^{ \circ  }C$