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Engineering
160 Views   |

The speed of sound in air at N.T.P. is 300 m/s. If air pressure becomes four times, then the speed of sound will be

• Option 1)

150 m/s

• Option 2)

300 m/s

• Option 3)

600 m/s

• Option 4)

1200 m/s

2

velocity is independent of pressure

Engineering
86 Views   |

Equation of progressive wave is given by $y=4 \sin \pi \left [ (\frac{t}{5}-\frac{x}{9})+\frac{x}{6} \right ]$ then which of the following is correct?

• Option 1)

n = 5 cm

• Option 2)

$\lambda = 18$ cm

• Option 3)

a = 0.04 m

• Option 4)

f = 50 Hz

As we learnt in  Travelling Wave Equation -   - wherein   wave length  Time period of oscillation         = Therefore,      Option 1) n = 5 cm Incorrect Option 2) cm Correct Option 3) a = 0.04 m Incorrect Option 4) f = 50 Hz Incorrect
Engineering
84 Views   |

Two waves are represented by $x_1=A \sin (\omega t +\frac{\pi}{6})$ and $x_2=A \cos \omega t$, then the phase difference between them is

• Option 1)

$\frac{\pi}{6}$

• Option 2)

$\frac{\pi}{2}$

• Option 3)

$\frac{\pi}{3}$

• Option 4)

$\pi$

As we learnt in  Travelling Wave Equation -   - wherein   wave length  Time period of oscillation                                                          Phase difference       Option 1) This option is incorrect. Option 2) This option is incorrect. Option 3) This option is correct. Option 4) This option is incorrect.
Engineering
123 Views   |

Two sounding bodies producing progressive wave given by $y_1=4 \sin 400 \, \, pt\, \, and \, \, y_2=4 \sin404\, \, pt$ are situated very near to the ears of a person who will hear

• Option 1)

2 beats per second with intensity ratio (4/3) between maxima and minima

• Option 2)

2 beats per second with intensity ratio (49/1) between maxima and minima

• Option 3)

4 beats per second with intensity ratio (7/1) between maxima and minima

• Option 4)

4 beats per second with intensity ratio (4/3) between maxima and minima

As we learnt in  Beat Frequency - module of   - wherein Where are frequency of two wave differ slightly  in value of frequency.    Beat frequency                                                        Ratio of Intensity maxima and minima              In the second equation           first equation   Option 1) 2 beats per second with intensity ratio (4/3) between maxima and minima This...
Engineering
101 Views   |

Two sound waves having a phase difference of 60° have path difference of

• Option 1)

$\lambda$

• Option 2)

$\frac{\lambda}{2}$

• Option 3)

$\frac{\lambda}{6}$

• Option 4)

$\frac{\lambda}{3}$

As we learnt in  Relation between phase difference and path difference - Phase difference -    Phase difference = (path difference) Path difference = (phase difference) =   Option 1) 2  This option is incorrect. Option 2) This option is incorrect. Option 3) This option is correct. Option 4) This option is incorrect.
Engineering
325 Views   |

Two sound waves are given by y = a sin (wt - kx) and y' = b cos (wt - kx). The phase difference between the two waves is

• Option 1)

$\frac{\pi}{2}$

• Option 2)

$\frac{\pi}{4}$

• Option 3)

$\pi$

• Option 4)

$\frac{3\pi}{4}$

As we learnt in  Travelling Wave Equation -   - wherein   wave length  Time period of oscillation     and Phase difference =   Option 1) This option is correct. Option 2) This option is incorrect. Option 3) This option is incorrect. Option 4) This option is incorrect.
Engineering
399 Views   |

Two passenger trains moving with a speed of 108 km/hour cross each other. One of them blows a whistle whose frequency is 1500 Hz. If sound speed is 330 m/s, then passengers sitting in the other train, after trains cross each other will hear sound whose frequency will be

• Option 1)

1250 Hz

• Option 2)

625 Hz

• Option 3)

1500 Hz

• Option 4)

900 Hz

As we learnt in  Frequency of sound when source & observer are moving away from each other -   - wherein Speed of sound Speed of observer speed of source Original frequency apparent frequency     Here both are moving away from each other   Option 1) 1250 Hz This option is correct. Option 2) 625 Hz This option is incorrect. Option 3) 1500 Hz This option is incorrect. Option 4) 900...
Engineering
152 Views   |

To demonstrate the phenomenon of beats we need

• Option 1)

Two sources which emit radiation of nearly the same frequency

• Option 2)

Two sources which emit radiation of exactly the same frequency

• Option 3)

Two sources which emit radiation of exactly the same frequency and have a definite phase relationship

• Option 4)

Two sources which emit radiation of exactly the same wavelength

As we learnt in  Beat Frequency - module of   - wherein Where are frequency of two wave differ slightly  in value of frequency.    Phenomena of beat frequency can be observed when two source of sound emit frequency of nearly same wave.   Option 1) Two sources which emit radiation of nearly the same frequency This option is correct. Option 2) Two sources which emit radiation of exactly the...
Engineering
154 Views   |

The wavelength is 600 cm when the source is stationary. If the source is moving with relative velocity of 60 m/sec towards the observer, then the wavelength of the sound wave reaching to the observer will be (velocity of sound = 330 m/s)

• Option 1)

98 cm

• Option 2)

60 cm

• Option 3)

49 cm

• Option 4)

120 cm

As we learnt in  Frequency of sound when observer is stationary and source is moving towards observer -   - wherein speed of sound speed of source original frequency apparent frequency       Option 1) 98 cm This option is incorrect. Option 2) 60 cm This option is incorrect. Option 3) 49 cm This option is correct. Option 4) 120 cm This option is incorrect.
Engineering
105 Views   |

The velocity of sound is measured in hydrogen and oxygen at a certain temperature. The ratio of the velocities is,

• Option 1)

1:1

• Option 2)

1:2

• Option 3)

1:4

• Option 4)

4:1

As we learnt in  Effect of temperature on speed of sound -   - wherein T is in Kelvin So velocity increses with increase in temperature.         Option 1) 1:1 This option is incorrect. Option 2) 1:2 This option is incorrect. Option 3) 1:4 This option is incorrect. Option 4) 4:1 This option is correct.
Engineering
105 Views   |

The velocity of sound in air at 4 atmosphere and that at 1 atmosphere pressure would be

• Option 1)

1 : 1

• Option 2)

4 : 1

• Option 3)

1 : 4

• Option 4)

3 : 1

As we learnt in  Effect of temperature on speed of sound -   - wherein T is in Kelvin So velocity increses with increase in temperature.      Since V is independent of P Ratio of velocity = 1:1   Option 1) 1 : 1 This option is correct. Option 2) 4 : 1 This option is incorrect. Option 3) 1 : 4 This option is incorrect. Option 4) 3 : 1 This option is incorrect.
Engineering
177 Views   |

The equation of a progressive wave traveling on a string is $y= 4\sin\frac{\pi}{2} \left (8t- \frac{\pi x}{8} \right )$ cm. The velocity of the wave is

• Option 1)

64 cm/s along + x direction.

• Option 2)

64 cm/s along - x direction.

• Option 3)

$(\frac{64}{\pi})$  cm/s along + x direction

• Option 4)

$\left ( \frac{64}{\pi} \right )$cm/s along - x direction

As we learnt in  Speed of sinusoidal wave - Wave Speed   - wherein         and  along +x direction.   Option 1) 64 cm/s along + x direction. This option is incorrect. Option 2) 64 cm/s along - x direction.  This option is incorrect. Option 3)   cm/s along + x direction This option is correct. Option 4) cm/s along - x direction This option is incorrect.
Engineering
78 Views   |

The equation of a progressive wave is given by, $y= 5 \sin p (\frac{t}{0.02}- \frac{x}{20})$  m, then the frequency of the wave is

• Option 1)

100 Hz

• Option 2)

50 Hz

• Option 3)

25 Hz

• Option 4)

10 Hz

As we learnt in  Travelling Wave Equation -   - wherein   wave length  Time period of oscillation                 [p should be ]   Option 1) 100 Hz This option is incorrect. Option 2) 50 Hz This option is incorrect. Option 3) 25 Hz This option is correct. Option 4) 10 Hz This option is incorrect.
Engineering
101 Views   |

The displacement y (in cm) produced by a simple harmonic wave is given by $y= \frac{10}{\pi}\sin(2000 \pi t- \frac{\pi x}{17})$the periodic time and maximum velocity of the particles in the medium will respectively be

• Option 1)

$10^{-3}$sec and 330 m/s

• Option 2)

$10^{-4}$ sec and 20 m/s

• Option 3)

$10^{-3}$ sec and 200 m/s

• Option 4)

$10^{-2}$ sec and 2000 cm/s.

As we learnt in  Relation between phase velocity and wave speed - - wherein  particle velocity wave velocity slope of curve     & particle velocity   Option 1) sec and 330 m/s This option is incorrect. Option 2)  sec and 20 m/s This option is incorrect. Option 3)  sec and 200 m/s This option is correct. Option 4)  sec and 2000 cm/s. This option is incorrect.
Engineering
151 Views   |

The amplitude of two waves are in the ratio 5:2. If all other conditions for the two waves are same, then what is the ratio of their energy densities?

• Option 1)

5 : 2

• Option 2)

10 : 4

• Option 3)

2.5 : 4

• Option 4)

25 :4

As we learnt in  Intensity of the wave - mass density angular frequency Amplitude Wave speed   - wherein flow of energy per unit area of cross section of the string in the unit time is known as intensity of wave.    Energy density     Option 1) 5 : 2 This option is incorrect. Option 2) 10 : 4 This option is incorrect. Option 3) 2.5 : 4 This option is incorrect. Option 4) 25 :4 This...
Engineering
112 Views   |

If V is the velocity of the wave and $\omega$ is the angular velocity, then the propagation constant (K) of the wave is given by

• Option 1)

$K=\frac{V}{\omega}$

• Option 2)

$K=\frac{\omega}{V}$

• Option 3)

$K=\frac{2\omega}{V}$

• Option 4)

$K=\frac{2V}{\omega}$

As we learnt in  Speed of sinusoidal wave - Wave Speed   - wherein    Relation between V & K is or   Option 1) This option is incorrect. Option 2) This option is correct. Option 3) This option is incorrect. Option 4) This option is incorrect.
Engineering
963 Views   |

If the amplitude of sound is doubled and the frequency reduced to one-fourth, the intensity of sound at the same point will be

• Option 1)

Increasing by a factor of 2

• Option 2)

Decreasing by a factor of 2

• Option 3)

Decreasing by a factor of 4

• Option 4)

Unchanged

As we learnt in  Intensity of the wave - mass density angular frequency Amplitude Wave speed   - wherein flow of energy per unit area of cross section of the string in the unit time is known as intensity of wave.    Intensity of sound   Option 1) Increasing by a factor of 2 This option is incorrect. Option 2) Decreasing by a factor of 2 This option is incorrect. Option 3) Decreasing by...
Engineering
191 Views   |

Frequency of tuning forks are 320 Hz and 325 Hz. If they are sounded together, the beat period is

• Option 1)

5 second

• Option 2)

6 second

• Option 3)

0 second

• Option 4)

0.2 second

As we learnt in  Beat Frequency - module of   - wherein Where are frequency of two wave differ slightly  in value of frequency.    Beat frequency = beat period = = 0.2 second   Option 1) 5 second This option is incorrect. Option 2) 6 second This option is incorrect. Option 3) 0 second This option is incorrect. Option 4) 0.2 second This option is correct.
Engineering
253 Views   |

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

Of these statements

• Option 1)

Both (A) and (R) are true and (R) is the correct explanation of (A)

• Option 2)

Both (A) and (R) are true but (R) is not the correct explanation of (A)

• Option 3)

(A) is true but (R) is false

• Option 4)

(A) is false but (R) is true

As we learnt in  Effect of density on speed of sound -   - wherein are ratio of specific heat. are densities.    Velocity of sound = In presence of moisture, average molar mass decreases and density of air decreases. Hence velocity of sound increases in moisture.   Option 1) Both (A) and (R) are true and (R) is the correct explanation of (A) This option is correct. Option 2) Both (A) and...
Engineering
105 Views   |

A wave equation which gives the displacement along the Y direction is given by $y= 10^{-4} \sin (60t + 2x)$, where x and y are in metres and t is time in seconds. This represents a wave

• Option 1)

Traveling with a velocity of 30 m/s in the negative x direction

• Option 2)

of wavelength x metre

• Option 3)

Of frequency $\left ( \frac{30}{\pi} \right )$hertz

• Option 4)

All of the above

As we learnt in  Travelling Wave Equation -   - wherein   wave length  Time period of oscillation   This represent a wave whose parameter are given below  =  60   K=2 It is moving along - X direction. All are corrrect. Option 1) Traveling with a velocity of 30 m/s in the negative x direction This option is incorrect. Option 2) of wavelength x metre This option is correct. Option 3) Of...
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