JEE Questions for Physics Waves Quiz 5 - MCQExams.com

If Fig. represents position of wave at t = 0, the equation of the wave can be written as
  • y = 0.6 sin (78.5x – 23600t)
  • y = 0.6 cos (78.5x – 23600t)
  • y = 0.6 sin (78.5x + 23600t)
  • y = 0.6 cos (78.5x + 23600t)

Physics-Waves-96167.png

  • Physics-Waves-96168.png
  • λ= 2π y0
  • λ = π/y0
  • λ = πy0/2
If the intensities of two interfering waves be I1 and I2, the contrast between maximum and minimum intensity is maximum, when
  • I1 >> I2
  • I1 < < I2
  • I1 = I2
  • Either I1 or I2 is zero
Two vibrating tuning forks produce progressive waves given by y1 = 4 sin 500 π t, y2 = 2 sin 506 π t and held near the ear of a person. Number of beats heard per minute is
  • 180
  • 3
  • 360
  • 60
Two mutually perpendicular simple harmonics vibration have same amplitude, frequency and phase. When they superimpose, the resultant form of vibration will be
  • A circle
  • An ellipse
  • A straight line
  • A parabola
Beats are produced by two travelling waves each of loudness I and nearly equal frequencies n1 and n2. The beat frequency will be … and maximum loudness heard will be….
  • (n1 – n2), 2I
  • (n1 – n2), 4I
  • (n1 + n2), 2I
  • (n1 – n2), I
In a sonometer, the waves produced are
  • longitudinal progressive
  • transverse progressive
  • transverse, stationary and polarised
  • transverse, stationary and unpolarised
A tuning fork produces 5 beats/sec. with a sonometer wire of lengths 40 cm and 44 cm, other factors remaining unchanged. The frequency of the tuning fork is
  • 80 Hz
  • 88 Hz
  • 160 Hz
  • 105 Hz
A 5.5 metre length of string has a mass of 0.035 kg. if the tension in the string is 77 N , the speed of a wave on the string is
  • 110 ms–
  • 165 ms–
  • 77 ms–
  • 102 ms–
Two parts of a sonometer wire divided by movable bridge differ in length by 0.2 cm and produce one beat per second, when sounded together. The total length of wire is one metre, then the frequencies are
  • 250.5 and 249.5 Hz
  • 230.5 and 229.5 Hz
  • 220.5 and 219.5 Hz
  • 210.5 and 209.5 Hz
Two closed organ pipes A and B have the same length A is wider than B. They resonate in the fundamental mode at frequencies. nA and nB respectively.
  • nA = nB
  • nA > nB
  • nA < nB
  • Either (b) or (c) depending on the ratio of their diameters
A pipe closed at one end produces a fundamental note of 412 hz. It is cut into two pieces of equal length. The fundamental frequencies produced in the two pieces are
  • 206 hz,412 hz
  • 824 hz, 1648 hz
  • 412 hz, 824 hz
  • 206 hz, 824 hz
In a resonance tube, using a tuning fork of frequency 325 hz, two successive resonance lengths are observed as 25.4 cm and 77.4 cm respectively. The velocity of sound in air is
  • 338 m/s
  • 328 m/s
  • 330 m/s
  • 320 m/s
A sound source is falling under gravity. At some time t=0, the detector lies vertically below source at a depth H as shown. if v is the velocity of sound and fө is frequency of the source, then the apparent frequency recorded after t = 2s is
Physics-Waves-96178.png

  • Physics-Waves-96179.png
  • 2)
    Physics-Waves-96180.png

  • Physics-Waves-96181.png

  • Physics-Waves-96182.png
A train has just completed a U-curve in a track which is a semi-circle. The engine is at the forward end of the semi-circular part of the track while the last carriage is at the rear end of the semi circular track. The driver blows a whistle of frequency 200Hz. Velocity of sound is 340m/sec. Then the appearent frequency as observed by a passenger in the middle of the train, when the speed of the train is 30 m/sec is
  • 181 Hz
  • 200 Hz
  • 188 Hz
  • 219 Hz
Two pulses in a stretched string whose centers are initially 8 cm apart are moving towards each other as shown in Fig. 11.18. The speed of each pulse is 2 cm/s. After 2 seconds the total energy of the pulses will be
Physics-Waves-96184.png
  • zero
  • purely Kinetic
  • purely potential
  • partly kinetic × partly potential
A sonometer wire resonates with a given tuning fork forming standing waves with five antinodes between the two bridges when a mass of 9 kg is suspended from the wire. When this mass is replaced by mass M, the wire resonates with the same tuning fork forming three antinodes for the same position of bridges. The value of M is
  • 25 kg
  • 5 kg
  • 12.5 kg

  • Physics-Waves-96185.png
The displacement y of a wave travelling in x-direction is given by, -4 y= 10 +sin (600t- 2x+ /π where x and y are in metre and t is in second. The speed of wave motion in ms-1 is
  • 300
  • 600
  • 1200
  • 200

Physics-Waves-96188.png

  • Physics-Waves-96189.png
  • 2)
    Physics-Waves-96190.png

  • Physics-Waves-96191.png

  • Physics-Waves-96192.png
In a stationary wave that forms as a result of reflection of waves from an obstacle, the ratio of the amplitude at an antinode to the amplitude at node is n. The fraction of energy reflection is.

  • Physics-Waves-96194.png
  • 2)
    Physics-Waves-96195.png

  • Physics-Waves-96196.png

  • Physics-Waves-96197.png
A heavy uniform rope hangs vertically from the ceiling, with its lower end free. A disturbance on the rope travelling upwards form the lower end has a velocity v at a distance x from the lower end such that
  • v ∝ x
  • 2)
    Physics-Waves-96199.png

  • Physics-Waves-96200.png

  • Physics-Waves-96201.png
A train has just completed a u-curve in a track, which a is semicircle. The engine is at the forward end of the semicircular part of the track, while the last carriage is at the rear end of the semicircular track. The driver blows a whistle of frequency 200 Hz. Velocity of sound is 340 m/s. Then the apparent frequency as observed by a passenger in the middle of the train, when the speed of the train is 30 m/s is
  • 219 Hz
  • 188 Hz
  • 200 Hz
  • 181 Hz
Three sound waves of equal amplitudes have frequencies (v –1 ), v, ( v + 1). They superpose to give beats. The number of beats produced per second will be …….
  • 3
  • 2
  • 1
  • 4

Physics-Waves-96204.png
  • λ=18 cm
  • v = 4 ms-1
  • a = 0.4 cm
  • f = 50 Hz

Physics-Waves-96206.png
  • π/4
  • π
  • π/3
  • π/2

Physics-Waves-96207.png
  • 30 ms-1
  • 40 ms-1
  • 300 ms-1
  • 400 ms-1

Physics-Waves-96208.png

  • Physics-Waves-96209.png
  • 2)
    Physics-Waves-96210.png

  • Physics-Waves-96211.png

  • Physics-Waves-96212.png

  • Physics-Waves-96213.png
The equation of a transverse wave travelling along positive X – axis with amplitude 0.2 m, velocity 360 ms-1 and wavelength 60 m can be written as

  • Physics-Waves-96214.png
  • 2)
    Physics-Waves-96215.png

  • Physics-Waves-96216.png

  • Physics-Waves-96217.png
A travelling wave represented by, y = a sin (ωt – kx) is superimposed on another wave represented by, y = a sin (ωt + kx). The resultant is

  • Physics-Waves-96218.png
  • a wave travelling along + x–direction
  • a wave travelling along – x–direction

  • Physics-Waves-96219.png

Physics-Waves-96220.png
  • 4.0 N
  • 12.5 N
  • 0.5 N
  • 6.25 N
A progressive wave y = a sin (kx – ωt) is reflected by a rigid wall at x = 0. Then, the reflected wave can be represented by,
  • y = asin (kx + ωt)
  • y = acos (kx + ωt)
  • y = –asin (kx - ωt)
  • y = –asin (kx + ωt)
  • y = acos (kx – ωt)
Beats are produced by frequencies v1 and v2(v1 > v2). The duration of time between two successive maximum or minimum is equal to

  • Physics-Waves-96221.png
  • 2)
    Physics-Waves-96222.png

  • Physics-Waves-96223.png

  • Physics-Waves-96224.png
An open organ pipe resonated with frequency f1 and 2nd harmonic. Now, one end is closed and the frequency is slowly increased, then it resonates with frequency f2 and nth harmonic, then

  • Physics-Waves-96225.png
  • 2)
    Physics-Waves-96226.png

  • Physics-Waves-96227.png

  • Physics-Waves-96228.png
Sound waves are passing through two routes-one in straight path and the other along a semicircular path of radius r and are again combined into one pipe and superimposed as shown in the figure. If the velocity of sound waves in the pipe is v, then frequencies of resultant waves of maximum amplitude will be integral multiples of
Physics-Waves-96229.png

  • Physics-Waves-96230.png
  • 2)
    Physics-Waves-96231.png

  • Physics-Waves-96232.png

  • Physics-Waves-96233.png
Fundamental frequency of a sonometer wire is n. If the length and diameter of the wire are doubled keeping the tension same, then the new fundamental frequency is

  • Physics-Waves-96234.png
  • 2)
    Physics-Waves-96235.png

  • Physics-Waves-96236.png

  • Physics-Waves-96237.png
A uniform wire of length L, diameter D and density p is stretched under a tension T. The correct relation between its fundamental frequency f, the length Land the diameter D is

  • Physics-Waves-96239.png
  • 2)
    Physics-Waves-96240.png

  • Physics-Waves-96241.png

  • Physics-Waves-96242.png
A long cylindrical tube carries a highly polished piston and has a side opening. A tuning fork of frequency v is sounded at the sound heard by the listener changes if the piston is moved in or out. At a particular position of the piston is moved through a distance of 9 cm, the intensity of sound becomes minimum, if the speed of sound is 360 m/s, the value of v is
Physics-Waves-96243.png
  • 129.6 Hz
  • 500 Hz
  • 1000 Hz
  • 2000 Hz
A car is moving along x-axis with a velocity v = 20 m/s. It sounds a whistle of frequency 660 Hz. If the speed of sound is 340 m/s, the apparent frequency heard by the observer O (shown in the figure) is
Physics-Waves-96244.png
  • 680 Hz
  • 640 Hz
  • 700 Hz
  • 720 Hz
An observer A sees an asteroid with a radioactive element moving by at a speed = 0.3 c and measure the radioactivity decay time to be TA. Another observer B is moving with the asteroid and measures its decay time as TB. Then TA and TBare related as
  • TB < TA
  • TA = TB
  • TB >TA
  • Either (or (depending on whether the asteroid is approaching or moving away from A

Physics-Waves-96245.png

  • Physics-Waves-96246.png
  • 2)
    Physics-Waves-96247.png

  • Physics-Waves-96248.png

  • Physics-Waves-96249.png
Each of the properties of sound in List I primarily depends on one of the quantities in List II. Select the correct answer (matching List I with List II) as per code given below the
Physics-Waves-96250.png
  • A = 1, B = 2, C = 3
  • A = 3, B = 2, C = 1
  • A = 2, B = 3, C = 1
  • A = 2, B = 1, C = 3
Which of the following functions represent a wave ?
  • (x – v t)2
  • In (x + v t)
  • e–(x– vt)2

  • Physics-Waves-96252.png
A light pointer fixed to one prong of a tunning fork touches a vertical smoked plate. The fork is set into vibration and the plate is allowed to fall freely. Eight complete waves are counted when the plate falls through 10 cm. the frequency of the tunning fork is
  • 112 Hz
  • 14Hz
  • 28Hz
  • 56Hz
From a point source, if amplitude of waves at a distance r is A, its amplitude at a distance 2r will be
  • A
  • 2A
  • A/2
  • A/4

Physics-Waves-96255.png
  • 3 cm
  • 1.5 cm
  • 6 cm
  • 4 cm
A sound wave travelling with a vel v in a medium A reaches a point on the interface of medium A and medium B. If the velocity in the medium B be 2 V, then the angle of incidence for total internal reflection of the wave will be
  • 15º
  • 30º
  • 45º
  • 90º
The following equations represent progressive transverse waves
Z1 = A cos ( ωt – KX)
Z2 = A cos ( ωt + KX)
Z3 = A cos ( ωt + KY)
Z4 = A cos ( ωt – KY)
A stationary wave will be formed by superposing
  • Z1 and Z2
  • Z1 and Z4
  • Z2 and Z3
  • Z3 and Z4

Physics-Waves-96258.png
  • 3 cm
  • 6 cm
  • 12 cm
  • 2 cm
The equation of a spherical progressive wave is
  • y = a sin ωt
  • y = a sin (ωt – kr)

  • Physics-Waves-96260.png

  • Physics-Waves-96261.png
A string of length L is stretched by L/20 and speed of transverse wave along it is v. The speed of wave when it is stretched by L/10 will be (assume Hook’s Law is obeyed)
  • 4 v
  • 2)
    Physics-Waves-96262.png
  • 2 v

  • Physics-Waves-96263.png
0:0:1


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