A hearing test is conducted on an aged person. It is found that her threshold of hearing is 20 dB at 1 kHz , and it rises linearly with frequency to, 60 dB at, 9 kHz . The minimum intensity of sound that the person can hear at, 5 kHz is,

0 . 05 times than that at 9 kHz

HARD

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In a test of subsonic Jet flies over head at an altitude of 100 m. The sound intensity on the ground as the Jet passes overhead is 160 dB. At what altitude should the plane fly so that the ground noise is not greater than 120 dB.

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Important Questions on Sound

HARD

Physics>Waves and Oscillations>Sound>Qualities of Sound

A particle performing S.H.M. starts from the equilibrium position and its time period is

16 s

. After

2 s

its velocity is

π m s^{- 1} .

Amplitude of oscillation is

(\cos 45^{o} = \frac{1}{\sqrt 2})

MEDIUM

Physics>Waves and Oscillations>Sound>Qualities of Sound

A string of length

1 m

and mass

5 g

is fixed at both ends. The tension in the string is

8 .0 N

. The string is set into vibration using an external vibrator of frequency

100 Hz

. The separation between successive nodes on the string is close to

HARD

Physics>Waves and Oscillations>Sound>Qualities of Sound

Two vectors

\vec{A}

and

\vec{B}

are defined as

\vec{A} = a \hat{i}

and

\vec{B} = a (\cos ω t \hat{i} + \sin ω t \hat{j})

, where a is a constant and

ω = \frac{π}{6} rad s^{- 1} .

|\vec{A} + \vec{B}| = \sqrt{3} |\vec{A} - \vec{B}|

at time

t = τ

for the first time, the value of

τ

in seconds, is_______

MEDIUM

Physics>Waves and Oscillations>Sound>Qualities of Sound

A hearing test is conducted on an aged person. It is found that her threshold of hearing is

20 dB

1 kHz

, and it rises linearly with frequency to,

60 dB

at,

9 kHz

. The minimum intensity of sound that the person can hear at,

5 kHz

is,

MEDIUM

Physics>Waves and Oscillations>Sound>Qualities of Sound

The intensity of sound during the festival season increased by,

100

times. This could imply a decibel level rise from-

MEDIUM

Physics>Waves and Oscillations>Sound>Qualities of Sound

A tunning fork of frequency

480 H z

is used in an experiment for measuring speed of sound

(v)

in air by resonance tube method. Resonance is observed to occur at two successive lengths of the air column,

l_{1} = 30 c m

and

l_{2} = 70 c m .

Then,

ν

is equal to:

MEDIUM

Physics>Waves and Oscillations>Sound>Qualities of Sound

A simple harmonic motion is represented by:

y = 5 (\sin 3 π t + \sqrt{3} \cos 3 π t) cm

The amplitude and time period of the motion are:

MEDIUM

Physics>Waves and Oscillations>Sound>Qualities of Sound

For a transvers wave travelling, along a straight line, the distance between two peaks (crests) is

5 m

, while the distance between one crest and one trough is

1.5 m

. The possible wavelengths (in

m

) of the waves are:

EASY

Physics>Waves and Oscillations>Sound>Qualities of Sound

The intensity of a sound appears to an observer to be periodic. Which of the following can be the cause of it?

MEDIUM

Physics>Waves and Oscillations>Sound>Qualities of Sound

A uniform rope of length

L

and mass

m_{1}

, hangs vertically from a rigid support. A block of mass

m_{2}

is attached to the free end of the rope. A transverse pulse of wavelength

λ_{1}

is produced at the lower end of the rope. The wavelength of the pulse when it reaches the top of the rope is

λ_{2}

. The ratio

\frac{λ_{2}}{λ_{1}}

is:

MEDIUM

Physics>Waves and Oscillations>Sound>Qualities of Sound

The pressure wave,

P = 0.01 \sin [1000 t - 3 x] N m^{- 2}

, corresponds to the sound produced by a vibrating blade on a day when atmospheric temperature is

0 ° C

. On some other day when temperature is

T

, the speed of sound produced by the same blade and at the same frequency is found to be

336 m s^{- 1}

. Approximate value of

T

is:

EASY

Physics>Waves and Oscillations>Sound>Qualities of Sound

Bass control in stereo system increases the power of

EASY

Physics>Waves and Oscillations>Sound>Qualities of Sound

A uniform thin rope of length

12 m

and mass

6 kg

hangs vertically from a rigid support and a block of mass

2 kg

is attached to its free end. A transverse short wave train of wavelength

6 cm

is produced at the lower and the rope. What is the wavelength of the wave train (in

cm

) when it reaches the top of the rope?

EASY

Physics>Waves and Oscillations>Sound>Qualities of Sound

A uniform string of length $20 m$ is suspended from a rigid support. A short wave pulse is introduced at its lowest end. It starts moving up the string. The time taken to reach the support is

(Take, $g = 10 m s^{- 2}$ )

MEDIUM

Physics>Waves and Oscillations>Sound>Qualities of Sound

When a particle of mass

m

is attached to a vertical spring of spring constant

k

and released, its motion, is described by

y (t) = y_{0} \sin^{2} ωt

, where '

y

' is measured from the lower end of upstretched spring. Then

ω

is :

EASY

Physics>Waves and Oscillations>Sound>Qualities of Sound

Sound waves of wavelength

λ

and velocity

v

in medium-

1

enter medium-

2

. If their velocity in medium-

2

4 v

, the wavelength in medium-

2

MEDIUM

Physics>Waves and Oscillations>Sound>Qualities of Sound

A transverse wave propagating on a stretched string of linear density $3 \times 10^{- 4} {kgm}^{- 1}$ is represented by the equation

$y = 0.2 \sin (1.5 x + 60 t)$

where, $x$ in metres and $t$ is in seconds. The tension in the string (in Newton) is

EASY

Physics>Waves and Oscillations>Sound>Qualities of Sound

A travelling harmonic wave is represented by the equation

y (x, t) = 10^{- 3} \sin (50 t + 2 x),

where

x

and

y

are in meter and

t

is in seconds. Which of the following is a correct statement about the wave?

EASY

Physics>Waves and Oscillations>Sound>Qualities of Sound

Which characteristic of sound, makes it possible to recognize a person by his voice without seeing him?

MEDIUM

Physics>Waves and Oscillations>Sound>Qualities of Sound

A small speaker delivers

2 W

of audio output. At what distance from the speaker will one detect

120 d B

intensity sound? [Given reference intensity of sound as

10^{- 12} W / m^{2}

]

In a test of subsonic Jet flies over head at an altitude of 100 m. The sound intensity on the ground as the Jet passes overhead is 160 dB. At what altitude should the plane fly so that the ground noise is not greater than 120 dB.

Important Questions on Sound

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