Sound Test

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Sound Test - 71

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Weekly Quiz Competition

Question 1
1 / -0

Statement 1: Loudness is the characteristic of a musical sound by which a loud sound can be distinguished from a faint sound.
Statement 2: Echo is always produced when sound is incident on the hard and polished surface.

A
Both statements 1 and 2 are true and statement 2 is the correct explanation of statement 1.

B
Both statements 1 and 2 are true but statement 2 is not the correct explanation of statement 1.

C
Statement 1 is true but statement 2 is false

D
Statement 1 is false but statement 2 is true

Solution

Loudness is the measure of the Amplitude of sound which distinguishes two sounds having different Amplitudes

Echo, on the other hand, is a reflection phenomenon that takes place when sound Is reflected from a hard and polished surface. Loose surfaces absorb most of the sound incident on them hence no echo occurs.

Both of the statements are correct but statement 2 is not the correct explanation of statement 1.

So, B is the correct answer.
Question 2
1 / -0

An echo is heard, if ____________ between the source and the reflector is atleast $$17\ m$$

A
Time

B
Distance

C
Arc length

D
None of these

Solution

Sound waves can be mirrored as can all waves. As a result of sound wave reflection from a large obstacle, the sound is heard which is named as an echo.
As the reflected sound gets merged with the original sound, echo is usually not heard. To hear an echo distinctly (as a separate sound) must be satisfied with certain conditions.
For about 0.1 seconds the sensation of any sound persists in our ear. That is known as hearing persistence.
When the echo is heard during this time span it is difficult to discern the original signal from its echo. So the most important condition for hearing an echo is that only after a lapse of at least 0.1 seconds after the original sound dies off, should the reflected sound reach the ear.
Since the sound speed is 340 m / s the sound traveling distance is 34 m in 0.1 seconds. The total distance between a sound source and the reflector is twice that. So, if the obstacle is at least 17 m away, then after 0.1 second, the reflected sound or the echo is clearly detected.
Hence, to hear a clear echo, the minimum distance between the reflecting surface and the observer is 17 m.
Question 3
1 / -0

Two identical sounds A and B reach a point in the same phase. The resultant sound is C. The loudness of C is n dB higher than the loudness of A. The value of n is?

A
$$2$$

B
$$3$$

C
$$4$$

D
$$6$$
Question 4
1 / -0

Directions For Questions

Ultrasonic and Infrasonic Waves: The sound having frequency between $$20$$ Hz to $$20$$ kHz is called audible sound. Human ear cannot hear sound of frequencies lying outside this range. The limits of audibility of sound vary from individual. Generally the upper limit decreases with increase of age of individual; usually and people can not hear sound of frequency more than $$15$$ kHz.
Sound of frequencies below $$20$$ Hz are called infrasonics, while frequencies beyond $$20$$ kHz are called ultrasonics. Ultrasonics can be heard by dogs, cat, bats, etc. Bats detect the path by means of ultrasonics. Ultrasonics can be used for diagnosis of turnover and other abnormalities within our body. This is known as ultrasonography. Ultrasonics are used to cure various diseases and to measure depth of oceans to detect submarines.

...view full instructions

The waves produced by simple pendulum (having time period $$2$$ seconds) are.

A
Infrasonics

B
Audible

C
Ultrasonic

D
None of these

Solution

According to the above discussion,

Sound Frequency
Infrasonics f < 20 kHz
Ultrasonic f > 20 kHz
Time period of simple pendulum $$T=2\ s$$

Frequency of pendulum $$f=\dfrac 1T=\dfrac 12=0.5\ Hz$$

Because frequency sound produced by a simple pendulum is less than 20 Hz, we can say that sound waves will be Infrasonics.
Option A
Question 5
1 / -0

Transverse waves can propagate

A
only in solid

B
both in solid and gases

C
neither in solid nor in gases

D
only in gases

Solution

Transverse wave can propagate in solids but not in liquids and gases.
Question 6
1 / -0

If the velocity of sound in a gas is 360 m/s and the distance between compression and the nearest rarefraction is 1m, then the frequency of sound is

A
90 Hz

B
180 Hz

C
360 Hz

D
720 Hz

Solution

Given,
$$v=360m/s$$
$$\dfrac{\lambda}{2}=1m$$
$$\lambda=2m$$
frequency, $$f=\dfrac{v}{\lambda}$$
$$f=\dfrac{360}{2}=180Hz$$
The correct option is B.
Question 7
1 / -0

A man standing on a cliff claps his hand and hears its echo after 1 sec.If the sound is reflected from another mountain then the distance between the man and the reflection points is V$$_{sound}$$ = 340m / sec.

A
$$680m$$

B
$$340m$$

C
$$170m$$

D
$$85m$$

Solution

Given,
$$V_{sound}=340m/s$$
Sound going reflect back in 1 sec. Sound reach mountain in $$t= 0.5sec$$.
Velocity of sound,
$$V_{sound}=\dfrac{d}{t}$$
$$d=V_{sound}.$$
$$t=340\times 0.5$$
$$=170m$$
The correct option is C.
Question 8
1 / -0

The nature of sound waves in gases is

A
Transverse

B
Longitudinal

C
Stationary

D
Electromagnetic

Solution

The sound waves produced in a medium are the longitudinal waves. Sound waves in air and fluids are longitudinal waves, because the particles that transport the sound vibrate parallel to the direction of the sound wave's travel.
Question 9
1 / -0

A girl claps in front of a wall and wind blows from the girl towards the wall at the speed of $$20 \ m/s$$. If she is standing at a distance of $$50 \ m$$ from the wall, then she will hear the echo of sound of claps approximately after [Speed of sound in still air = $$330 \ m/s$$]

A
$$0.3 \ s$$

B
$$0.6 \ s$$

C
$$1.2 \ s$$

D
$$0.9 \ s$$

Solution
Question 10
1 / -0

Some whistles are designed to produce waves that can attract the attention of dogs but humans do not notice these waves. What kind of waves are these?

A
These are normal sounds waves whose frequency is less than $$20\ Hz$$. Humans cannot hear them because these waves have frequencies below the audible range.

B
These are normal sounds waves whose frequency is more than $$20,000\ Hz$$. Humans cannot hear them because these waves have frequencies above the audible range.

C
These are electromagnetic waves.

D
These are supersonic sound waves.

Solution

A dog whistle (also known as a silent whistle or Galton's whistle) is a type of whistle that emits sound in the ultrasonic range, which most humans cannot hear but some other animals can, including dogs and domestic cats, and is used in their training.

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Sound	Frequency
Infrasonics	f < 20 kHz
Ultrasonic	f > 20 kHz

Sound Test - 71

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Sound Test - 71

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SHARING IS CARING

Question 1

Both statements 1 and 2 are true and statement 2 is the correct explanation of statement 1.

Both statements 1 and 2 are true but statement 2 is not the correct explanation of statement 1.

Statement 1 is true but statement 2 is false

Statement 1 is false but statement 2 is true

Solution

Question 2

Time

Distance

Arc length

None of these

Solution

Question 3

$$2$$

$$3$$

$$4$$

$$6$$

Question 4

Infrasonics

Audible

Ultrasonic

None of these

Solution

Question 5

only in solid

both in solid and gases

neither in solid nor in gases

only in gases

Solution

Question 6

90 Hz

180 Hz

360 Hz

720 Hz

Solution

Question 7

$$680m$$

$$340m$$

$$170m$$

$$85m$$

Solution

Question 8

Transverse

Longitudinal

Stationary

Electromagnetic

Solution

Question 9

$$0.3 \ s$$

$$0.6 \ s$$

$$1.2 \ s$$

$$0.9 \ s$$

Solution

Question 10

These are normal sounds waves whose frequency is less than $$20\ Hz$$. Humans cannot hear them because these waves have frequencies below the audible range.

These are normal sounds waves whose frequency is more than $$20,000\ Hz$$. Humans cannot hear them because these waves have frequencies above the audible range.

These are electromagnetic waves.

These are supersonic sound waves.

Solution

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