A whistle producing sound waves of frequencies 9500 Hz and above

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 Multiple Choice QuestionsMultiple Choice Questions

1.

Match List-I (Electromagnetic wave type) with List-II (Its association/application) and select the correct option from the choices given below the lists:

  List I   List II
A. Infared waves 1. To treat muscular strain
B. Radio waves 2. For broadcasting
C. X -rays 3. To detect fracture of bones
D. Ultraviolet 4. Absorbed by the ozone layer of the atmosphere

  • A B C D
    4 3 2 1
  • A B C D
    1 2 4 3
  • A B C D
    3 2 1 4
  • A B C D
    3 2 1 4
536 Views

2.

The transverse displacement y(x,t) of a wave on a string is given by
straight y left parenthesis straight x comma straight t right parenthesis space equals space straight e to the power of negative left parenthesis ax squared plus bt squared space plus space 2 square root of ab space xt right parenthesis end exponent
This represents a

  • wave moving in +x direction with speed square root of straight a over straight b end root

  • wave moving in -x direction with speed square root of b over a end root

  • standing wave frequency square root of straight a

  • standing wave frequency square root of straight a

573 Views

3.

In amplitude modulation, sinusoidal carrier frequency used is denoted by ωc and the signal frequency is denoted by ωm. The bandwidth (Δωm) of the signal is such that Δωm << ωc. Which of the following frequencies is not contained in the modulated wave?

  • ωm + ωc

  • ωc - ωm

  • ωm

  • ωm

1079 Views

4.

An observer is moving with half the speed of light towards a stationary microwave source emitting waves at frequency 10 GHz. What is the frequency of the microwave measured by the observer?
(speed of light = 3 × 108 ms–1)

  • 17.3 GHz

  • 15.3 GHz

  • 10.1 GHz

  • 10.1 GHz

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5.

Three sound waves of equal amplitudes have frequencies (ν – 1), ν, (ν + 1). They superpose to give beats. The number of beats produced per second will be.

  • 4

  • 3

  • 2

  • 2

898 Views

6.

A wave travelling along the x-axis is described by the equation y(x, t) = 0.005 cos (αx −βt). If the wavelength and the time period of the wave are 0.08 m and 2.0 s, respectively, then α and β in appropriate units are 

  • α = 25.00 π, β = π

  • α = 0.08/ π,  2.0/π

  • α = 0.04 / π , β =1.0/π

  • α = 0.04 / π , β =1.0/π

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7.

A whistle producing sound waves of frequencies 9500 Hz and above is approaching a stationary person with speed v ms−1. The velocity of sound in air is 300 ms−1. If the person can hear frequencies upto a maximum of 10,000 Hz, the maximum value of v upto which he can hear the whistle is

  • 15 square root of 2 space ms to the power of negative 1 end exponent
  • 15 divided by square root of 2 space ms to the power of negative 1 end exponent
  • 15 ms-1

  • 15 ms-1


C.

15 ms-1

straight f subscript app space equals space fraction numerator straight f left parenthesis 300 right parenthesis over denominator 300 minus straight v end fraction
rightwards double arrow space straight v space equals space 15 space straight m divided by straight s
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8.

When two tuning forks (fork 1 and fork 2) are sounded simultaneously, 4 beats per second are heard. Now, some tape is attached on the prong of the fork 2. When the tuning forks are sounded again, 6 beats per seconds are heard. If the frequency of fork 1 is 200 Hz, then what was the original frequency of fork 2?

  • 200 Hz

  • 202 Hz

  • 196 Hz

  • 196 Hz

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9.

An observer moves towards a stationary source of the sound, with a velocity one-fifth of the velocity of sound. What is the percentage increase in the apparent frequency?

  • 0

  • 0.5%

  • 5%

  • 5%

496 Views

10.

The displacement y of a particle in a medium can be expressed as y = 10−6 sin(110t + 20 x + π/4) m, where t is in seconds and x in a meter. The speed of the wave is

  • 2000 m/s

  • 5 m/s

  • 20 m/s

  • 20 m/s

310 Views

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