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

Earn 100

If given graph represents the variation of displacement wave for sound wave in an air tube. Which will be the pressure variation for tube?

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Important Questions on Sound Waves

MEDIUM

Physics>Oscillations and Waves>Sound Waves>Sound as a Pressure Wave

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:

HARD

Physics>Oscillations and Waves>Sound Waves>Sound as a Pressure Wave

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})

EASY

Physics>Oscillations and Waves>Sound Waves>Sound as a Pressure Wave

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

EASY

Physics>Oscillations and Waves>Sound Waves>Sound as a Pressure Wave

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

MEDIUM

Physics>Oscillations and Waves>Sound Waves>Sound as a Pressure Wave

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

MEDIUM

Physics>Oscillations and Waves>Sound Waves>Sound as a Pressure Wave

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:

MEDIUM

Physics>Oscillations and Waves>Sound Waves>Sound as a Pressure Wave

The intensity of sound during the festival season increased by,

100

times. This could imply a decibel level rise from-

MEDIUM

Physics>Oscillations and Waves>Sound Waves>Sound as a Pressure Wave

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

MEDIUM

Physics>Oscillations and Waves>Sound Waves>Sound as a Pressure Wave

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:

HARD

Physics>Oscillations and Waves>Sound Waves>Sound as a Pressure Wave

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_______

EASY

Physics>Oscillations and Waves>Sound Waves>Sound as a Pressure Wave

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?

MEDIUM

Physics>Oscillations and Waves>Sound Waves>Sound as a Pressure Wave

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>Oscillations and Waves>Sound Waves>Sound as a Pressure Wave

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 :

MEDIUM

Physics>Oscillations and Waves>Sound Waves>Sound as a Pressure Wave

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}

]

MEDIUM

Physics>Oscillations and Waves>Sound Waves>Sound as a Pressure Wave

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:

MEDIUM

Physics>Oscillations and Waves>Sound Waves>Sound as a Pressure Wave

A transverse wave propagating along $x$ -axis is represented by

$y (x, t) = 8.0 \sin (0.5 π x - 4 π t - \frac{π}{4})$

where $x$ is in meters and $t$ is in seconds. The speed of the wave is

EASY

Physics>Oscillations and Waves>Sound Waves>Sound as a Pressure Wave

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>Oscillations and Waves>Sound Waves>Sound as a Pressure Wave

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,

EASY

Physics>Oscillations and Waves>Sound Waves>Sound as a Pressure Wave

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>Oscillations and Waves>Sound Waves>Sound as a Pressure Wave

The air pressure at sea level is

101325 Pa

. At the centre of a rarefaction of a sound wave in air, the pressure is

91000 Pa

. Which is the most likely pressure at the centres of a compression of the same wave?

If given graph represents the variation of displacement wave for sound wave in an air tube. Which will be the pressure variation for tube?

Important Questions on Sound Waves

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