If the speed of the wave shown in the figure is 330m/s in the given medium, then the equation of the wave propagating in the positive x-direction will be (all quantities are in M.K.S. units) :

  • y=0.05sin2π(4000 t−12.5 x)

  • y=0.05sin2π(4000 t−122.5 x)

  • y=0.05sin2π(3300 t−10 x)

  • y=0.05sin2π(3300 x−10 t)

The displacement-time graphs for two sound waves A and B are shown in the figure, then the ratio of their intensities IA/IB is equal to :

  • 1 : 4

  • 1 : 16

  • 1 : 2

  • 1 : 1

A wave motion has the function y=a0sin(ω t−kx). The graph in figure shows how the displacement y at a fixed point varies with time t. Which one of the labeled points shows a displacement equal to that at the position x=π2k at time t = 0

  • P

  • Q

  • R

  • S

The graph between wave number (v¯) and angular frequency (ω) is
  • 1
  • 2
  • 3
  • 4

The speed of sound in a gas is v and the r.m.s. velocity of the gas molecules is c. The ratio of v to c is:

  •  3γ                                 

  •  γ3

  •  3γ                               

  •  γ3

Assertion: In a stationary wave, there is no transfer to energy.

Reason: There is no outward motion of the disturbance from one particle to adjoining particle in a stationary wave.

  1. If both the assertion and the reason are true and the reason is a correct explanation of the assertion
  2. If both the assertion and reason are true but the reason is not a correct explanation of the assertion
  3. If the assertion is true but the reason is false
  4. If both the assertion and reason are false
  • 1
  • 2
  • 3
  • 4

Three sound waves of equalamplitudes have frequencies of (n-1), (n), and (n + 1). They superimpose to give beats. The number of beats produced per second will be

  •   1

  •   4

  •   3

  •   2

A tuning fork is used to produce resonance in a glass tube. The length of the air column in this tube can be adjusted by a variable piston. At room temperature of 27°C , two successive resonances are produced at 20 cm and 73 cm column length. If the frequency of the tuning fork is 320 Hz, the velocity of sound in air at 27°C is:

  • 330 m/s

  • 339 m/s

  • 350 m/s

  • 300 m/s

The fundamental frequency in an open organ pipe is equal to the third harmonic of a closed organ pipe. If the length of the closed organ pipe is 20 cm, the length of the open organ pipe is:

  • 13.2 cm

  • 8 cm

  • 12.5 cm

  • 16 cm

If the intensity is increased by a factor of 20; then how many decibels in the sound level increased?

  • 18

  • 13

  • 9

  • 7

A source of sound S emitting waves of frequency 100 Hz and an observer O are located at some distance from each other. The source is moving with a speed of 19.4 ms-1 at an angle of 600 with the source-observer line as shown in the figure. The observer is at rest. The apparent frequency observed by the observer (velocity of sound in air 330 ms-1), is: 

  • 100 Hz

  • 103 Hz

  • 106 Hz

  • 97 Hz

1. 8.0 JK-1 mol-1

 

  •   8.5 JK-1 mol-1    

  •  7.5 JK-1 mol-1

  •  7.0 JK-1 mol-1

  • 0 gm of gas occupies 22.4 litres at NTP. The specific heat capacity of the gas at constant volume is  5.0 JK-1 mol-1. If the speed of sound in the gas at NTP is 952 ms-1, then the molar heat capacity at constant pressure will be: Take R=8.31 JK-1 mol-1

The fundamental frequency of a closed organ pipe of a length 20 cm is equal to the second overtone of an organ pipe open at both ends. The length of the organ pipe open at both ends will be:
 
  • 80 cm
  • 100 cm
  • 120 cm
  • 140 cm

If we study the vibration of a pipe open at both ends, then the following statement is not true:

  • Odd harmonics of the fundamental frequency will be generated

  • All harmonics of the fundamental frequency will be generated

  • Pressure change will be maximum at both ends

  • The open end will be an antinode

A wave travelling in the +ve x-direction having maximum displacement along y-direction as 1 m, wavelength 2π m and frequency of 1π Hz, is represented by:
1. y=sin2πx-2πt
2. y=sin10πx-20πt
3. y=sin2πx+2πt
4. y=sinx-2t
  • 1
  • 2
  • 3
  • 4
Sound waves travel at 350 m/s through the warm air and at 3500 m/s through brass.A 700 Hz acoustic wave entering brass from warm air has the following wavelength:

  •   increase by a factor 20

  •   increase by a factor 10

  •   decrease by a factor 20

  •   decrease by a factor 10

A wave in a string has an amplitude of 2 cm.The wave travels in the positive direction of the x-axis with a speed of 128 m/s and it is noted that 5 complete waves fit in 4 m length of the string. The equation describing the wave is:

  • y = (0.02)m sin(7.85x+1005t)

  • y = (0.02)m sin(15.7x -2010t)
  • y = (0.02)m sin(15.7x+2010t)
  • y = (0.02)m sin(7.85x -1005t)

The driver of a car travelling with speed 30 m/s towards a hill sounds a horn of frequency 600 Hz. If the velocity of sound in air is 330 m/s the frequency of reflected sound as heard by the driver is:

  • 550 Hz

  • 555.5 Hz

  • 720 Hz

  • 500 Hz

Each of the two strings of lengths 51.6 cm and 49.1 cmis tensioned separately by 20 N of force. The mass per unit length of both the strings is the same and equals 1 g/m. When both the strings vibrate simultaneously, the number of beats is:
 
  • 5
  • 7
  • 8
  • 3

Two sound waves with wavelength 5.0 m and 5.5 m, respectively, propagates in gas with a velocity of 330 m/s. We expect the following number of beats per second:

  • 12

  • 0

  • 1

  • 6

A transverse wave propagating along the x-axis is represented by: 
y(x,t) = 8.0 sin 0.5πx-4πt-π4 where x is in meters and t is in seconds. The speed of the wave is:

  •  4π m/s

  •  0.5 m/s

  •  π4 m/s

  •  8 m/s

The time of reverberation of a room A is one second. What will be the time (in seconds) of reverberation of a room, having all the dimensions double of those of room A ?

  • 1

  • 2

  • 4

  •  12

Which one of the following statements is true?

  • Both light and sound waves in the air are transverse.

  • The sound waves in the air are longitudinal while the light waves are transverse.

  • Both light and sound waves in the air are longitudinal.

  • Both light and sound waves can travel in a vacuum.

Statement–1 : In the case of a stationary wave,
a person hear a loud sound at the pressure nodes
as compared to the antinodes.
and
Statement–2 : In a stationary wave all the
particles of the medium vibrate in phase.

  • Statement-1 is True, Statement-2 is True,
  • Statement-2 is a correct explanation for
  • statement-1

  • 2. Statement-1 is True, Statement-2 is True,

  • Statement-2 is NOT a correct explanation
  • for Statement-1

  • 3. Statement-1 is True, Statement-2 is False

A steel rod 100 cm long is clamped at its middle. The fundamental frequency of the longitudinal vibrations of the rod is given to be 2.53 kHz. What is the speed of sound in steel?

  • 5.12 km/s

  • 5.06 km/s

  • 4.29 km/s

  • 4.01 km/s

Two waves of amplitudes A0 and xA0 pass through a region. If x>1, the difference in the maximum and minimum resultant amplitude possible is:

  •  (x+1)A0

  •  (x-1)A0

  •  2xA0

  •  2A0

A : The propagation of sound in air should be an isothermal process.

R : As air is bad conductor of heat, its temperature does not change by compression or expansion.

  1. If both the assertion and the reason are true and the reason is a correct explanation of the assertion
  2. If both the assertion and reason are true but the reason is not a correct explanation of the assertion
  3. If the assertion is true but the reason is false
  4. If both the assertion and reason are false
  • 1
  • 2
  • 3
  • 4

What is sound level for intensity of 10–6 W/m2?

  • 50 dB 

  • 60 dB

  • 70 dB 

  • 80 dB

The rate of energy transfer in a wave depends

  • directly on the square of the wave amplitude and square of the wave frequency

  • directly on the square of the wave amplitude and square root of the wave frequency

  • directly on the wave frequency and square of the wave amplitude

  • directly on the wave amplitude and square of the wave frequency

A tuning fork with a frequency of 800 Hz produces resonance in a resonance column tube with the upper end open and the lower end closed by the water surface. Successive resonances are observed at lengths of 9.75 cm, 31.25 cm, and 52.75 cm. The speed of sound in air is:

  • 500 m/s

  • 156 m/s

  • 344 m/s

  • 172 m/s

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