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InterviewSolution
This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 51. |
Two sound waves with wavelengths 5.0 cm and 5.5 cm, respectively each propagate in a gas with velocity 330 m/s. The number of beats per second will be ……..(a) 0 (b) 1 (c) 6 (d) 12 |
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Answer» Correct answer is (c) 6 Number of beats/s is = 330 [\(\frac{1}{5} - \frac{1}{5.5}\)]= 6 |
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| 52. |
Transverse waves can propagate …… (a) both in a gas and in a metal (b) in a gas but not in a metal (c) not in a gas but in a metal (d) neither in a gas nor in a metal |
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Answer» (a) not in a gas but in a met |
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| 53. |
Mechanical Waves (a) are longitudinal only (b) are transverse only (c) can be both longitudinal and transverse.(d) are neither longitudinal for transverse waves. |
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Answer» (c) can be both longitudinal and transverse. |
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| 54. |
What is common in mechanical longitudinal and transverse waves? |
| Answer» both longitudinal and transverse waves can propagate through solids. | |
| 55. |
The pressure variation in a sound wave is given by `DeltaP=8cos(4.00x-3000t+(pi)/(4))` Find its displacement amplitude. The density of the medium is `10^(3)" kg "m^(-3)`. |
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Answer» `DeltaP_(0)=BAK` Also, `B=rhov^(2)` `thereforeDeltaP_(0)=rhoV^(2)Ak` But `V^(2)=(omega^(2))/(k^(2))` `thereforeDeltaP_(0)=(rho omega^(2))/(k^(2))Ak=(rho omega^(2)A)/(k)` or `A=((DeltaP_(0))k)/(rho omega^(2))=(8xx4.00)/(10^(3)xx(3000)^(2))=3.55xx10^(-9)m` |
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| 56. |
What do you mean by wave motion? Discuss Its four important characteristics. |
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Answer» Wave motion is a motion where the energy is transferred without shifting the material particles. Four characteristics: 1. It is a Simple Harmonic Motion. 2. Energy is transported without material shift. 3. The velocity of waves depends on the medium (only for longitudinal waves). 4. The particles oscillate in SHM. |
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| 57. |
Given below are some examples of wave motion. Statein each case if the wave motion is transverse, longitudinal or a combinatin of both. (a) Motion of kink in a longitudinal spring produced by displacing one end of the spring sideways. (b) Waves produced in a cylinder containing a liquid by moving its piston back and forth. (c ) Waves produced by a motorboat sailing in water. (d) Ultrasonic waves in air produced by a vibrating quartz crystal. |
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Answer» (a) Transverse and logitudinal (b) Longitudinal (c ) Transverse and longitudinal (d) Longitudinal |
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| 58. |
Given below are some examples of wave motion. State in each case, if the wave motion is transverse, longitudinal or a combination of both? (i) Motion of a kink in a long coil spring produced by displacing one end of spring side ways. (ii) Waves produed in a cylinder containing a liquid by moving its piston back and forth. (iii) Waves produed by a motor boat sailing in water. (iv) Light waves travelling from sun to earth. (v) ultrasonic waves in air produced by a vibrating quartz crystal. |
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Answer» (a) Transverse and longitudinal (b) Longitudinal (c) Transverse and longitudinal (d) Longitudinal |
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| 59. |
Given below are some examples of wave motion. State In each case If the motion is transverse, longitudinal or a combination of both. 1. Motion of a kink In a long coil spring produced by displacing one end of the spring sideways. 2. Wave produced in a cylinder containing water by moving its piston back and forth. 3. Wave produced by a motorboat sailing in water. 4. Ultrasonic waves In air produced by a vibrating crystal. |
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Answer» 1. Longitudinal wave 2. Transverse wave 3. Combination of both 4. Longitudinal wave |
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| 60. |
Explain why (or how) solids can support both longitudinal and transverse waves, but only longitudinal waves can propagate in gases. |
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Answer» This is due to fact that gases have only the bulk modulus of elasticity, whereas solids have both, the shear modulus as well as the bulk modulus of elasticity. |
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| 61. |
Consider the following function: (a) y = x2 + 2 α tx (b) y = (x + vt) 2which among the above function can be characterized as a wave? |
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Answer» (a) y = x2 + 2 α tx. This expression is not a wave equation. (b) y = (x + vt)2 . This expression is satisfies the wave equation. |
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| 62. |
Why is it that transverse waves cannot be produced in a gas? Can the transverse waves can be produced in solids and liquids? |
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Answer» Transverse waves travel in the form of crests and through. They involve changes in the shape of the medium. As gas has no elasticity of shape, hence transverse waves cannot be produced in it. So, they can be transmitted through media which sustain shearing stress such as solids, strings and liquid surface. |
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| 63. |
`y(xt)=asin(kx-omegat+phi)` represents aA. wave travelling in the negative direction of x-axisB. Wave travelling in the positive direction of x-axisC. stationary waveD. combination of two stationary waves |
| Answer» Correct Answer - B | |
| 64. |
Waves of wavelength `lamda` are generated on the water surface. The phase difference between two points at a distance of `lamda` isA. `pi` radianB. `2pi` radianC. `(pi)/(2)` radianD. `(pi)/(6)` radian |
| Answer» Correct Answer - B | |
| 65. |
Transverse mechanical waves cannot be propagated throughA. solidsB. liquidsC. gasesD. Both (2) and (3) |
| Answer» Correct Answer - D | |
| 66. |
A sonometer wire of length `1.5m` is made of steel. The tension in it produces an elastic strain of `1%`. What is the fundamental frequency of steel if density and elasticity of steel are `7.7 xxx 10^(3) kg//m^(3)` and `2.2 xx 10^(11) N//m^(2)` respectively ?A. (a) `188.5 Hz`B. (b) `178.2 Hz`C. ( c ) `200.5 Hz`D. (d) `770 Hz` |
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Answer» Correct Answer - B (b) Fundamental frequency, `f = (v)/(2l) = (1)/(2l)sqrt((T)/(mu)) = (1)/(2l)sqrt((T)/(Arho))[`because` `v = sqrt((T)/(mu))` and `mu = (m)/(l)]` Also,`Y = (Tl)/(ADeltal)` rArr `(T)/(A) = (YDeltal)/(l)` rArr `f = (1)/(2l)sqrt((gammaDeltal)/(lrho))` ........(i) Putting the value of `l`, `(Deltal)/(l)`, `rho` and `gamma` i n `eq^(n)`. (i)we get, `f = sqrt((2)/(7)) xx (10^(3))/(3)` or, `f~~ 178.2 Hz` |
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| 67. |
What is the evidence in support of the fact that:(a) Sound is a wave;(b) Sound is a mechanical wave;(c) Sound waves are longitudinal waves. |
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Answer» (a) Diffraction of sound waves. (b) Requires material medium for propagation (c) Sound wave can not be polarized |
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| 68. |
Explosions on other planets are not heard on earth. Why? |
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Answer» This is because no material medium is present over a long distance between earth and planets and is absence of material medium for propagation, sound waves cannot travel. |
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| 69. |
Why longitudinal waves are called pressure waves? |
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Answer» Because propagation of longitudinal waves through a medium, involves changes in pressure and volume of air, when compressions and rarefactions are formed. |
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| 70. |
A whistle of frequency 500 Hz tied to the end of a string of length 1.2 m revolves at 400 rev / min . A listener standing some distance away in the plane of rotation of whistle hears frequencies in the range (speed of sound = 340 m / s )A. 436 to 586B. 426 to 574C. 426 to 584D. 436 to 674 |
| Answer» Correct Answer - A | |
| 71. |
Statement-1: Doppler formula is not applicable, when detector is moving away from source with speed greater than that of sound. Statement-2: There is always a decrease in pitch of sound if detector moves towards source.A. Statement-1 is true, statement-2 is true, statement-2 is a correct explanation for statement-1B. Statement-1 is true, statement-2 is true, statement-2 is not a correct explanation for statement-1C. statement-1 is true, statement-2 is falseD. statement-1 is false, statement-2 is true |
| Answer» Correct Answer - C | |
| 72. |
Doppler effect is applicable forA. sound waves onlyB. light waves onlyC. both sound and light wavesD. None of these |
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Answer» Correct Answer - C The Doppler effect is applicable for both sound and light waves. |
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| 73. |
The two nearest harmonics of a tube closed at one end and open at other end are 220 Hz and 260 Hz. What is the fundamental frequency of the system?A. 10HzB. 20 HzC. 30 HzD. 40 Hz |
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Answer» Correct Answer - b |
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| 74. |
A boat at anchor is rocked by waves of velocity 25m/s, having crests 100 m apart. The boat bounches up once in every (a) 4.0s (b) 2500s (c) 0.25s (d) 75s |
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Answer» (a) 4.0s λ = distance between crests = 100 m frequency v = \(\frac{25}{100} = \frac{1}{4} S^{-1}\) Therefore, the crests reach the boat once every 4 seconds. |
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| 75. |
For the harmonic travelling wave y = 2 cos 2π (10t–0.0080x + 3.5) where x and y are in cm and t is second. What is the phase difference between the oscillatory motion at two points separated by a distance of(a) 4 m(b) 0.5 m(c) λ/2(d) 3λ/4 (at a given instant of time)(e) What is the phase difference between the oscillation of a particle located at x = 100cm, at t = T s and t = 5 s? |
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Answer» (a) 6.4π radian, (b) 0.8π radian, (c) π radian, (d) 3π /2 radian, (e)80π radian. |
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| 76. |
What will be the resultant amplitude when 2 waves y1 = a sin ω t are superposed at any point at a particular instant? |
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Answer» y = y1 + y2 = a sin ω t + a cos ω t = a (sin ω t + cos ω t) = √2a (sin (ω t + π/4) ∴ Resultant amplitude : √2a. |
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| 77. |
For the travelling harmonic wave `y ( x,t) = 2.0 cos 2pi``( 10t- 0.0080x+0.35)` where x and yare in cm and t in s. Calculate the phase differencebetween oscillatory motion of two points separated by a distance of a) 4m, (b) 0.5m (c ) `lambda //2` (d) `3lambda //4` |
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Answer» The given equation be written as `y =2.0 cos [ 2p( 10t-0.0080x) + 2pi xx0.35]` `y =2.0 cos[ 2pi xx 0.0080 ((10t)/(0.0080) -x)+ 0.7 pi]` Compare it with the standard equation of a travelling harmonic ,we have `y =r . Cos[(2pi)/(lambda) (vt-x) + ph_(0)]` We get, `(2pi)/( lambda)= 2pixx0.0080` Further ,we know that phase diff. `phi=( 2pi)/( lambda) x ` (a) Whe `x = 4m= 400 cm ` `phi =( 2pi)/(lambda).x =2pixx0.0080xx400` `= 6.4 pi rad.` (b) When`x =0.5=50 cm` `phi= ( 2pi)/( lambda ) .x = 2pixx0.0080 xx50` `= 0.8 pi ` rad. (c ) When `x = ( lambda)/(2)` `phi = ( 2pi)/( lambda) xx( lambda )/(2)= pi`rad. (d) When `x= (3 lambda)/( 4)` `phi = ( 2pi)/( lambda) xx ( 3 lambda)/( 4) = ( 3lambda)/(2)` rad. |
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| 78. |
A sonometer wire for which the length of the vibrating segment is 1.5 m is vibrating in its first overtone. It is in unison with a tuning fork of frequency 256Hz. Calculate the speed of the waves in the wire. |
| Answer» Correct Answer - 384 `ms^(-1)` | |
| 79. |
A sonometer wire is vibrating in the second overtone. In the wire there are …… (a) two nodes and two antinodes(b) one node and two antinodes(c) four nodes and three antinodes(d) three nodes and three antinodes |
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Answer» (c) four nodes and three antinodes |
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| 80. |
A ship in a sea sends SONAR waves straight down into the seawater from the bottom of the ship. The signal reflects from the deep bottom bed rock and returns to the ship after 3.5 s. After the ship moves to 100 km it sends another signal which returns back after 2s. Calculate the depth of the sea in each case and also compute the difference in height between two cases. |
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Answer» Speed of SONAR waves in water c = 1500 ms-1 Time taken to reflect from the bottom of the sea, 2t = 3.5 sec ∴ t = 1.75 sec Distance covered in forward and reflected backward (d1) = c × t d2 = 1500 × 1.75 = 2625 m After ship moves in a distance = 150 km Time taken to reflect by the waves 2t = 2s t = 1s Distance covered by the waves (d2) = c × t = 1500 × 1 = 1500 m The different between the height of two cases = 2625 – 1500 hdifference = 1124 m |
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| 81. |
What is meant by RADAR and SONAR? How are long distances measured using these techniques? |
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Answer» 1. RADAR – Radio Detecting and Ranging. 2. SONAR – Sound Navigation and Ranging The waves produced by the devices are sent and are reflected by the bodies and reach them back. If the speed of sound is known and the time taken for to and fro journey, the distance can be estimated. |
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| 82. |
What does RADAR mean? |
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Answer» RADAR stands for "Radio detection and Ranging" It is a device used for locating the position of an aeroplane, and also finding its velocity. |
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| 83. |
Explain why (or how) a violin note and sitar note may have the same frequency, yet we can distinguish between the two notes. |
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Answer» The quality of a violin note is different from the quality of sitar. Therefore, they emit different harmonics which can be observed by human ear to differentiate between the two notes. |
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| 84. |
Explain why (or how):1. A violin note and sitar note may have the same frequency, yet we can distinguish between the two notes, 2. Solids can support both longitudinal and transverse waves, but only longitudinal waves can propagate In gases, and 3. The shape of a pulse gets distorted during propagation in a dispersive medium. |
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Answer» 1. Because they emit different harmonies which can be easily differentiated by human ears. 2. This is because solids have both shear and bulk modulus of elasticity whereas gas has only bulk modulus of elasticity. 3. A sound pulse consists of waves with different wavelengths. In a dispersive medium, these waves travel with different velocities which distorts the shape of pulse. |
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| 85. |
What do you mean by overtones? |
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Answer» "The frequencies produced by the vibrating bodies other than the fundamental frequency are called overtones." |
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| 86. |
The velocity of sound in air is 332 ms-1. Find the frequency of the fundamental note of an open pipe 50 cm long. |
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Answer» ν0 = v/2L = {332}/{2 x 0.5} = 332 ms-1 |
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| 87. |
Explain why is it NOT possible to have interference between the waves produced by 2 sitars? |
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Answer» Because the waves produced will not have a constant phase difference. |
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| 88. |
Why is it not possible to have interference between the waves produced by a violin? |
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Answer» This is because the sound produced will not have a constant phase relationship. |
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| 89. |
The transverse displacement of a string clamped at its both ends is given by `y(x,t)=2sin((2pi)/3x)cos(100pit)` where x and y are in cm and t is in s. Which of the following statements is correct?A. All the points on the string between two consecutive nodes vibrate with same frequency, phase and amplitude.B. All the points on the string between two consecutive nodes vibrate with same frequency and phase but different amplitude.C. All the points on the string between two consecutive nodes vibrate with different frequency and phase but same amplitude.D. All the points on the string between two consecutive nodes vibrate with different frequency, phase and amplitude |
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Answer» Correct Answer - B The given equation is `y(x,t)=2sin((2pi)/3x)cos(100pit)` It represents a stationary wave. Therefore, all the points between consecutive nodes vibrate with same frequency and same phase but different amplitude. |
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| 90. |
The transverse displacement of a string clamped at its both ends is given by `y(x, t) = 0.06 sin ((2pi)/3 x) cos(l20pit)` where x and y are in m and t in s. The length of the string is 1.5 m and its mass is `3 xx 10^(-2)` kg. The tension in the string isA. 324 NB. 648 NC. 832 ND. 972 N |
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Answer» Correct Answer - B The given equation is `y(x,t)=0.06 sin((2pi)/3x)cos(120pit)` Compare it with y(x, t) = 2a sin kx cos `omega`t we get, k`=(2pi)/3or(2pi)/lamda=(2pi)/3orlamda=3 m` and `omega = 120pi: or 2piupsilon = 120pi or upsilon =- 60 Hz = 60 s^(-1)` Velocity of wave, `v = upsilonlamda = (60 s^(- 1)) (3 m) = 180 m s^(-1)` Mass per unit length of the string, `mu=(3xx10^(-2)kg)/(1.5m)=2xx10^(-2)kgm^(-1)` Velocity of transverse wave in the string, v `v=sqrt(T/mu)orv^(2)=T/muorT=v^(2)mu` `T=(180ms^(-1))^(2)(2xx10^(-2)kgm^(-1))=648 N` |
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| 91. |
The transverse displacement of a string (clamped at its both ends) is given by y (x,t) = 0.06 sin (2πx/3) cos (120πt). All the points on the string between two consecutive nodes vibrate with(a) same frequency(b) same phase(c) same energy(d) different amplitude. |
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Answer» (a) same frequency (c) same energy (d) different amplitude. |
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| 92. |
The amplitude of a wave represented by the equation `y=3sin(5x-0.5t)+4cos(5x-0.5t)`, isA. 7B. 4C. 3D. 5 |
| Answer» Correct Answer - D | |
| 93. |
During propagation of a plane progressive mechanical wave(a) all the particles are vibrating in the same phase.(b) amplitude of all the particles is equal.(c) particles of the medium executes S.H.M.(d) wave velocity depends upon the nature of the medium. |
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Answer» (b) amplitude of all the particles is equal. (c) particles of the medium executes S.H.M. (d) wave velocity depends upon the nature of the medium. |
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| 94. |
The difference between the frequencies of the third and fifth harmonic of a closed organ pipe is 100 Hz. Its fundamental frequency isA. 100 HzB. 50 HzC. 25 HzD. 12.5 Hz |
| Answer» Correct Answer - B | |
| 95. |
What property of the medium is essential for the propagation of mechanical wave? |
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Answer» Elasticity and Inertia. |
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| 96. |
Statement-1: On moon you cannot hear your friend standing at some distance from you Statement-2: There is vacuum on moon.A. Statement-1 is true, statement-2 is true, statement-2 is a correct explanation for statement-1B. Statement-1 is true, statement-2 is true, statement-2 is not a correct explanation for statement-1C. statement-1 is true, statement-2 is falseD. statement-1 is false, statement-2 is true |
| Answer» Correct Answer - A | |
| 97. |
Two waves of same frequency and intensity superimpose on each other in opposite phases. After the superposition the intensity and frequency of waves will.A. increaseB. decreaseC. remain constantD. become zero |
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Answer» Correct Answer - d |
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| 98. |
Two waves of same frequency and intensity superimpose on each other in opposite phases. After the superposition the intensity and frequency of waves will.A. If both assertion and reason are true and reason is the correct explanation of assertion.B. If both assertion and reason are true but reason is not the correct explanation of assertion.C. If assertion is true but reason is false.D. If both assertion and reason are false. |
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Answer» Correct Answer - A The principle of superposition is basic to the phenomenon of interference. |
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| 99. |
With the propagation of a longitudinal wave through a material medium, the quantities transmitted in the propagation direction areA. matterB. energyC. energy and matterD. energy, matter and momentum |
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Answer» Correct Answer - B During the propagation of longitudinal wave in a medium. Energy not the matter is transmitted through the medium. |
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| 100. |
A transverse harmonic wave on a string is described by y (x,t ) = 3.0 sin (36t + 0.018x + π/4) where x and y are in cm and t is in s. The positive direction of x is from left to right.(a) The wave is travelling from right to left.(b) The speed of the wave is 20m/s.(c) Frequency of the wave is 5.7 Hz.(d) The least distance between two successive crests in the wave is 2.5 cm. |
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Answer» (a) The wave is travelling from right to left. |
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