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Important Questions on Sound Waves

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Physics>Oscillations and Waves>Sound Waves>Speed of Sound in Gases

A bomb explodes at time

t = 0

in a uniform, isotropic medium of density

ρ

and releases energy

E

, generating a spherical blast wave. The radius

R

of this blast wave varies with time

t

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Physics>Oscillations and Waves>Sound Waves>Speed of Sound in Gases

Two waves of sound of wavelength

1.2 m

and

1.25 m

in a medium produce

90

beats in

10 s .

The speed of sound in the medium is

MEDIUM

Physics>Oscillations and Waves>Sound Waves>Speed of Sound in Gases

A sound wave of frequency

200 Hz

is travelling in air. The speed of sound in the air is

340 m s^{- 1} .

What is the phase difference at a given instant between two points separated by a distance of

85 cm

along the direction of propagation?

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Physics>Oscillations and Waves>Sound Waves>Speed of Sound in Gases

When sound travels from air to water the quantity that remains unchanged is

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Physics>Oscillations and Waves>Sound Waves>Speed of Sound in Gases

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

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Physics>Oscillations and Waves>Sound Waves>Speed of Sound in Gases

The velocity of sound in air is independent of change in

MEDIUM

Physics>Oscillations and Waves>Sound Waves>Speed of Sound in Gases

Consider a gas with molar mass

M .

If the sound at frequency

f

is introduced to a tube of this gas at temperature

T

then an internal acoustic standing wave is set up with nodes separated by

L .

The adiabatic constant

(γ = \frac{C_{p}}{C_{v}})

HARD

Physics>Oscillations and Waves>Sound Waves>Speed of Sound in Gases

A person in front of a mountain is beating a drum at the rate of

40

per minute and hears no distinct echo. If the person moves

90 m

closer to the mountain, he has to beat the drum at

60

per minute to not hear any distinct echo. The speed of sound is

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Physics>Oscillations and Waves>Sound Waves>Speed of Sound in Gases

It takes

2.0

seconds for a sound wave to travel between two fixed points when the day temperature is

10 ° C

. If the temperature rises to

30 ° C

, the sound wave travels between the same fixed parts in

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Physics>Oscillations and Waves>Sound Waves>Speed of Sound in Gases

A hospital uses an ultrasonic scanner to locate tumors in a tissue. The operating frequency of the scanner is

4.2 MHz .

The speed of sound in a tissue is

1.7 km / s .

The wavelength of sound in the tissue is

HARD

Physics>Oscillations and Waves>Sound Waves>Speed of Sound in Gases

Sound travels in a mixture of two moles of helium and

n

moles of hydrogen. If rms speed of gas molecules in the mixture is

\sqrt{2}

times the speed of sound, then the value of

n

will be

MEDIUM

Physics>Oscillations and Waves>Sound Waves>Speed of Sound in Gases

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:

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Physics>Oscillations and Waves>Sound Waves>Speed of Sound in Gases

The speed of sound in air at NTP is

332 m / s

. If air pressure becomes four times the normal then the speed of sound waves will

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Physics>Oscillations and Waves>Sound Waves>Speed of Sound in Gases

Sound travels fastest in

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Physics>Oscillations and Waves>Sound Waves>Speed of Sound in Gases

Consider the following statements :
(A) The velocity of sound in air increases due to presence of moisture in it.
(R) The presence of moisture in air lowers the density of air.
In the above statements:

MEDIUM

Physics>Oscillations and Waves>Sound Waves>Speed of Sound in Gases

Let the speed of sound at

0 ° C

332 {m s}^{- 1}

. On a winter day sound travels

342 m

in one second. The atmospheric temperature on that day is

MEDIUM

Physics>Oscillations and Waves>Sound Waves>Speed of Sound in Gases

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>Speed of Sound in Gases

Consider a system of gas of a diatomic molecule in which the speed of sound at

0^{o} C

1260 m s^{- 1}

. Then, the molecular weight of the gas is in

g {mol}^{- 1}

, (given, the gas constant

R

8 .314 J {mol}^{- 1} K^{- 1}

)

MEDIUM

Physics>Oscillations and Waves>Sound Waves>Speed of Sound in Gases

STATEMENT - 1: The basic of Laplace correction was the exchange of heat between the region of compression and rarefaction in air is not possible. Because

STATEMENT - 2: Air is a bad conductor of heat and velocity of sound in air is large.

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Physics>Oscillations and Waves>Sound Waves>Speed of Sound in Gases

The Newton's formula for the velocity of the longitudinal waves in a medium is expressed as

What kind of weather is the most uncomfortable?

Important Questions on Sound Waves

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