Sound Test

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Sound Test - 28

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Weekly Quiz Competition

Question 1
1 / -0

Time period of a sound wave is $$10\ ms$$. What is the frequency of the sound wave?

A
50 Hz

B
100 Hz

C
200 Hz

D
400 Hz

Solution

Given
$$T= 10\ ms = \dfrac{1}{1000} = 10^{-2}\ s$$
We know
$$f= \dfrac{1}{T}$$
$$f= \dfrac{1}{10^{-2}} = 100\ Hz$$
Question 2
1 / -0

If velocity of sound in air is 340 $$m s^{-1}$$, calculate frequency when wavelength is 0.85 m :

A
400 Hz

B
240 Hz

C
340 Hz

D
385 Hz

Solution

The relationship between the velocity of the sound, its wavelength and frequency is given by the formula $$v=\lambda \times f$$,

where, $$v$$ - velocity of the wave

$$\lambda $$- wavelength of the wave

$$f$$ - frequency of the wave.

In the question, it is given that the velocity of the wave is 340 m/s and the wavelength is 0.85 m.

Now the frequency is calculated as follows.
$$v=\lambda \times f$$,

That is, $$f=\dfrac { v }{ \lambda } $$.

$$f=\dfrac { 340 }{ 0.85m } = 400 Hz$$.

Hence, the frequency of the wave is 400 Hz.
Question 3
1 / -0

In the bell jar experiment, as air is removed from the jar :

A
intensity of sound falls

B
speed of sound falls

C
intensity of sound increase

D
speed of sound increases.
Question 4
1 / -0

The loudness of sound is determined by the

A
amplitude of vibration

B
ratio of amplitude and frequency of vibration

C
frequency of vibration

D
product of amplitude and frequency of vibration

Solution

The amplitude of sound determines the loudness of sound. A sound that is faint will have a small amplitude while that of a loud sound will have larger amplitude.
Question 5
1 / -0

If a wave completes 20 vibrations in 2.5s, then its frequency is

A
20 Hz

B
8 Hz

C
200 Hz

D
50 Hz

Solution

Frequency is the number of vibration per second.
So in this case the frequency of the wave is:
$$f=\dfrac{20}{2.5} Hz$$ $$=8\ Hz$$
Question 6
1 / -0

A tuning fork makes $$256$$ vibrations per second in air. When the speed of sound is $$330 \ m/s$$, the wavelength of the note emitted is :

A
$$0.56 \ m$$

B
$$0.89 \ m$$

C
$$1.11 \ m$$

D
$$1.29 \ m$$

Solution

$$\textbf{Step 1 - Finding the wavelength}$$
As given velocity $$v= 330\ m/s$$ and $$\text{frequency}\space f = 256\ Hz$$
$$\because v = f \times \lambda$$
$$\Rightarrow 330 = 256\times \lambda \Rightarrow \lambda = \dfrac {330}{256} = 1.29\ m$$

Hence wavelength $$= 1.29\ m$$

Thus option (D) is correct.
Question 7
1 / -0

1 hertz is equal to

A
1 vibration per minute

B
10 vibrations per minute

C
60 vibrations per minute

D
600 vibrations per minute

Solution

Hertz is the unit of frequency.
$$1\ Hz = 1\ vibration\ per\ sec = 60\ vibrations\ per\ minute$$
Question 8
1 / -0

Lightning can be seen the moment it occurs. Paheli observes lightning in her area. She hears the sound 5 s after she observed lightning. How far is she from the place where lightning occurs? (Speed of sound $$= 330$$ m/s)

A
1.65 km

B
1.75 km

C
3.3 km

D
3.5 km

Solution

The distance between two points is calculated using the given formula.
Distance = Speed $$\times $$Time.
Given that the speed of sound in air is 330 meters per second and the time taken is 5 seconds, distance covered can be calculated as follows.
$$D=330m/s\times 5s = 1650 m$$
Hence, Paheli is at a distance of 1.65 kilometers from the lightning spot.
Question 9
1 / -0

A sound wave travels at a speed of 339 m/s . If its wavelength is 1.5 cm , what is the frequency of the wave?

A
$$2600 \ Hz$$

B
$$2200 \ Hz$$

C
$$2260 \ Hz$$

D
$$22600 \ Hz$$

Solution

Given speed $$(V)= 339 m/s $$ ; $$\lambda= 0.0015 \ m ; \ f=?$$
Now we know, $$ V= f \lambda $$
$$ \implies f= \dfrac{V}{\lambda}= \dfrac{339}{0.0015}= 22600 \ Hz$$
Question 10
1 / -0

Pitch of sound is determined by its

A
frequency

B
amplitude

C
speed

D
loudness

Solution

A pitch is a characteristic of sound that we generally use to distinguish shrill sound from a grave sound. The pitch increases with increase in frequency and decrease with decrease in frequency.

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Re-Attempt Weekly Quiz Competition

Sound Test - 28

Result

Sound Test - 28

Score

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Rank

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SHARING IS CARING

Question 1

50 Hz

100 Hz

200 Hz

400 Hz

Solution

Question 2

400 Hz

240 Hz

340 Hz

385 Hz

Solution

Question 3

intensity of sound falls

speed of sound falls

intensity of sound increase

speed of sound increases.

Question 4

amplitude of vibration

ratio of amplitude and frequency of vibration

frequency of vibration

product of amplitude and frequency of vibration

Solution

Question 5

20 Hz

8 Hz

200 Hz

50 Hz

Solution

Question 6

$$0.56 \ m$$

$$0.89 \ m$$

$$1.11 \ m$$

$$1.29 \ m$$

Solution

Question 7

1 vibration per minute

10 vibrations per minute

60 vibrations per minute

600 vibrations per minute

Solution

Question 8

1.65 km

1.75 km

3.3 km

3.5 km

Solution

Question 9

$$2600 \ Hz$$

$$2200 \ Hz$$

$$2260 \ Hz$$

$$22600 \ Hz$$

Solution

Question 10

frequency

amplitude

speed

loudness

Solution

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