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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.
| 151. |
An engine driver moving towards a wall with velocity of `50ms^(-1)` emits a note o frequency 1.2kHz. The frequyency of note after reflection from the wall is eard by the engine driver when speed of sound in air is `350ms^(-1)` is A. 1kHzB. 1.8kHzC. 1.6kHzD. 1.2kHz |
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Answer» Correct Answer - C |
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| 152. |
An engine driver moving towards a wall with a velocity of 60 m/s emits a note of 1400 Hz. Speed of sound in air is 340 m/s .The frequency of the note after reflection from the wall as heard by the engine driver isA. 1600 HzB. 1200 HzC. 1000 HzD. 2000 Hz |
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Answer» Correct Answer - A |
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| 153. |
The velocity of sound in air at `14^@ C` is `340 ms^(-1)`.What will it be when the pressure is doubled and temperature is raised to `157.5^@ C`? |
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Answer» Correct Answer - `416.4 ms^(-1)` |
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| 154. |
If velocity of sound in hydrogen at `0^(@)C` is `1280 ms^(-1)` , what will be the velocity of sound at the same temperature in a mixture, 2 parts in volume of hydrogen to one part of oxygen. Density of oxygen is 16 times that of hydrogen. |
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Answer» Correct Answer - `640 ms^(-1)` |
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| 155. |
A and B are two point sources of sound (of same frequency) and are kept at a separation. At a point `P`, the intensity of sound is observed to be `I_(0)` when only source A is put on. With only B on the intensity is observed to be `2I_(0)`. The distance `AP` is higher than distance `BP` by half the wavelength of the sound. Find the intensity recorded at `P` with both sources on. Give your answer for following cases: (a) The sources are coherent and in phase. (b) The sources are coherent and 180° out of phase. (c) The sources are incoherent. |
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Answer» Correct Answer - (a) `0.2 I_(0)` (b) `(3+2sqrt(2))I_(0)` (c) `3 I_(0)` |
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| 156. |
Two sound sources oscillate in phase with a frequency of `100` Hz. At a point `1.74` m from one source and `1.16` m from the other, the amplitudes of sound from the two sources are A and 2 A respectively. Calculate the amplitude of the resultant disturbance at the point. [Speed of sound in air is `v = 348 ms^( –1)`] |
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Answer» Correct Answer - `sqrt(7) A` |
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| 157. |
In (Q. 27.) the distance of plucking poing from the fixed end isA. 5 cmB. 10 cmC. 2.5 cmD. 7.5 cm |
| Answer» Correct Answer - C | |
| 158. |
A wave pulse on a string on a string has the dimension shown in figure. The wave speed is v=1 cm /s . If point O is a free end. The shape of wave at time t = 3s si A. B. C. D. |
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Answer» Correct Answer - D |
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| 159. |
A tuning fork vibrates with a frequency of 256. If the speed of sound is `345.6 ms^(-1)`., Find the wavelength and the distance, which the sound travels during the time, the fork makes 60 vibrations. |
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Answer» Correct Answer - 1.35 m,81 m |
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| 160. |
A plane prohressive wave is given by `y=2 cos 6.284 (330t-X)`. What is period of the wave?A. `1/330 s`B. `2 pi xx 330 s`C. `(2 pi xx330)^(-1) s`D. `6.284/330 s` |
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Answer» Correct Answer - A We have the progressive wave given by `y=2 cos 6.284 (330t-x)` `=2 cos 2 pi (330 t-x)` `=2 cos (2pi xx330 t-2 pi x)` `omega=2pi xx330`, and time period, `T=(2pi)/omega =1/330 s`. |
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| 161. |
The amplitude of a wave disturbance propagating along positive X-axis is given by `=1/(1+x^(2))` at t=0 and `y=1/[1+(x-2)^(2)]` at t=4 s where x and y are in metre. The shape of wave diturbance does not change with time. The velocity of the wave isA. 1 m/sB. 0.5 m/sC. 2 m/sD. 4 m/s |
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Answer» Correct Answer - B |
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| 162. |
A wave is represented by the equation `y=0.5 sin (10 t-x)m`. It is a travelling wave propagating along the + x direction with velocityA. `40 ms^(-1)`B. `20 ms^(-1)`C. `5 ms^(-1)`D. None of these |
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Answer» Correct Answer - D Compare the given equation with the standard form `y = sin [(2pi t)/T+(2pi x)/lambda]` `(2pi)/T=10, (2pi)/lambda =1` `implies v=lambda/T=10/1=10 ms^(-1)` |
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| 163. |
The maximum displacement of any particles either sides of mean position when a progressive wave is propagating through a medium isA. antinodeB. amplitudeC. nodeD. wavelength |
| Answer» Correct Answer - B | |
| 164. |
The similarity between the sound waves and light waves isA. travel at the same speed in airB. can show interference phenomenonC. can pass through any mediumD. are transverse waves |
| Answer» Correct Answer - B | |
| 165. |
The sound wave require more reflecting surface than the light wave because ofA. longer wavelengthB. low speedC. high speedD. lower wavelength |
| Answer» Correct Answer - A | |
| 166. |
When a wave is reflected at a rarer surface,the change in phase isA. `(pi)/(2)` radB. `pi` radC. `3(pi)/(4)` radD. 0 |
| Answer» Correct Answer - D | |
| 167. |
The echo and the original sound differ in the following characteristics of a musical noteA. intensityB. qualityC. pitchD. all of the above |
| Answer» Correct Answer - A | |
| 168. |
Pitch of a musical note depends uponA. amplitude of soundB. the frequency of soundC. the instrumentD. none of these |
| Answer» Correct Answer - B | |
| 169. |
If sound waves reflected from the denser medium, then there isA. no change in phaseB. only there is reverse of particle velocityC. change in phase by `180^(@)` between incident and reflected wavesD. reversion of wave velocity only |
| Answer» Correct Answer - C | |
| 170. |
Build up a musical scale of music with 288 Hz as the key note. |
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Answer» Correct Answer - 324,360,384,432,480,540,576 Hz |
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| 171. |
Wavelength of two musical motes in air are `18/35 m` and `(90/173)m`. Each note produces four beats per second with a third note of frequency `f_(0)`. Calculate the frequency `f_(0)`. |
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Answer» Correct Answer - 696 Hz |
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| 172. |
In (Q. 10.) the ratio of particle velocity amplitude and wavelength isA. `pi`B. `2pi`C. `3pi`D. `4pi` |
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Answer» Correct Answer - D We know that, `k=(2pi)/(100)` or `(2pi)/(lambda)=(2pi)/(100)` `therefore " "lambda = 100 cm` But `v_("Particle")=(del y)/(del t) = a omega cos (omega t - kx)` `(v_("Particle"))_("max")= a omega = 4 xx (2pi)/(0.02)=400 pi cm//s` `therefore " "(v_("Particle"))_("max")/(lambda)=(400 pi)/(100)= 4pi` |
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| 173. |
The transverse displacement `y(x, t)` of a wave on a string is given by `y(x, t)= e ^(-(ax^(2) + bt^(2) + 2sqrt((ab))xt)`. This represents a :A. wave moving in - x-direction with speed `sqrt((b)/(a))`B. standing wave of frequency `sqrt(b)`C. standing wave of frequency `(1)/(sqrt(b))`D. wave moving in + x-direction with speed `sqrt(a//b)` |
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Answer» Correct Answer - A `y(x, t) = e^(-(ax^(2)+bt^(2)+2sqrt(ab) xt))=e^(-(sqrt(a)x+sqrt(b)t)^(2)` It is a function of type `y = f(omega t + kx)` `therefore y (x, t)` represents wave travelling along - x-direction, Speed of wave = `(omega)/(k)=(sqrt(b))/(sqrt(a))=sqrt((b)/(a))` |
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| 174. |
The fundamental tone produced by an organ pipe has a frequency of 110 Hz. Some other frequencies produced by the pipe are 220, 440, 550, 660 Hz. Is this pipe open or closed?Calculate effective length of the pipe. Speed of sound is 330m`//`s. |
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Answer» Correct Answer - Pipe is open at both ends, 1.5 m |
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| 175. |
A source of sound is moving with a constant speed of 20 m/s emitting a note of a fixed frequency. The ratio of the frequencies observed by a stationary observer when the source is approaching him and after it has crossed him is (V = 340 m/s)A. `9 : 8`B. `8 : 9`C. `10 : 9`D. `9 : 10` |
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Answer» Correct Answer - A `(n_(1))/(n_(2)) = (v + v_(s))/(v - v_(s)) = (340 + 20)/(340 - 20) = (360)/(320)= (9)/(8)` |
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| 176. |
A steel wire of length `64 cm` weighs `5 g`. If it is stretched by a force of `8 n`N` what would be the speed of transverse wave passing on it? |
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Answer» Correct Answer - A::B::C `v =sqrt((T)/(mu))` |
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| 177. |
Two blocks each having a mass of `3.2 kg` are connected by a wire CD and system is suspended from the ceiling by another wire AB. The linear mass density of the wire AB is `10 gm^(-1) and that of `CD` is `8 gm^(-1)`. Find the speed of a transverse wave pulse produced in AB and in CD. |
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Answer» Correct Answer - A::C::D `T_(CD) = 3.2 g, T_(AB) = 6.4 g` and `v = sqrt((T)/(mu))` |
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| 178. |
the equation of a wave travelling along the positive x - axis ,as shown in figure at t = 0 is given by A. `sin (kx - omegat+ pi/6)`B. `sin (kx - omegat- pi/6)`C. `sin (omegat -kx+ pi/6)`D. `sin (omegat - kx- pi/6)` |
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Answer» Correct Answer - D |
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| 179. |
In what time after its motion begins, will a particle oscillating according to the equation, `y=7 sin 0.5 pi ` t move from the mean position to maximum displacement ?A. 0.5 sB. 1.5 sC. 1sD. 2s |
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Answer» Correct Answer - C `y = 7 sin 0.5 pit` `omega = 0.5 pi` `T = (2pi )/(omega) = (2pi)/(0.5 pi) = 4` `t = (T)/(4) = (4)/(4) = 1s` |
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| 180. |
Stationary wave of frequency 5 K Hz is produced in a tube open at both ends and filled with air at `300 K`. The tube is oscillating in its first overtone mode. (a) Find the length of the tube assuming that air contains only nitrogen and oxygen in molar ratio of `3 : 1`. (b) What shall be the frequency of sound wave used so that the same tube oscillates in its second overtone mode? |
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Answer» Correct Answer - (a) 6.9 cm (b) 7543 Hz |
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| 181. |
As a wave propagates,Which of the following is a wrong option?A. the wave intensity remains constant for a plane waveB. the wave intensity decrease as the inverse of the distance from the source for a spherical wavesC. the wave intensity decreases as the inverse square of the distance from the source for a spherical wave.D. total intensity of the spherical wave over the spherical surface remians constant at all times,while source is at the centre of spherical surface. |
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Answer» Correct Answer - D |
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| 182. |
In a wave motion `y = sin (kx - omega t),y` can represent :-A. electric fieldB. magnetic fieldC. displacement, pressureD. All of these |
| Answer» Correct Answer - D | |
| 183. |
In (Q. 24.) the tension in string is T and the linear mass density of string is `mu`. The ratio of magnitude of maximum velocity of particle and the magnitude of maximum acceleration isA. `(1)/(2pi)sqrt((mul^(2))/(T))`B. `2pisqrt((mul^(2))/(T))`C. `(1)/(2pi)sqrt((T)/(mul^(2)))`D. `(1)/(4pi)sqrt((mul^(2))/(T))` |
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Answer» Correct Answer - A Here, `v_("max")=Aomega=2aomega` (at antinode A = 2a) and acceleration is `f_("max") = omega^(2)A=2aomega^(2)` `therefore" Ratio "=(2a omega)/(2a omega^(2))=(1)/(omega)` `because` Frequency, `v = (n)/(2l) sqrt(((T)/(mu))) = (2)/(2l) sqrt(((T)/(mu)))` (for second harmonic, n = 2) `=sqrt(((T)/(mu l^(2))))` `because " "omega=2piv` `therefore" Ratio "=(1)/(2piv)` `= (1)/(2pi) sqrt(((mu l^(2))/(T)))` |
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| 184. |
A non-uniform wire of length `l` and mass `M` has a variable linear mass density given by `mu = kx`, where `x` is distance from one end of wire and `k` is a constant. Find the time taken by a pulse starting at one end to reach the other end when the tension in the wire is `T`. |
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Answer» Correct Answer - B::C `M = int_(0)^(L)kx dx = (kL^(2))/(2)` `:. k = (2M)/(L^(2)` `v_(x) = sqrt((T)/(mu_(x))) = sqrt((T)/(kx))= sqrt((T)/((2M//L^(2)) x))` `=(Lsqrt((T)/(2M)))x^(-1//2) = (dx)/(dt)` `:. int_(0)^(t) dt = (1)/(L) sqrt((2M)/(T))int_(0)^(L)x^(1//2) dx` or `t=((2)/(3L)sqrt((2M)/(T)))L^(3//2)` `=(2)/(3) sqrt((2ML)/(T)` |
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| 185. |
In case of mechanical wave a partical oscillates and during sacillation its kinetic energy and potential energy changes. |
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Answer» Correct Answer - (a)P,Q (b)R,S (c )P,S,(d)Q,R |
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| 186. |
A small piece of cork in a ripple tank oscillates us and down as ripples pass it. If the ripples travelling at 0.3 m/s, have a wavelength of `1.5 pi` cm and the cork vibrates with an amplitude of 5mm, then the maximum velocity of the cork will beA. 20 cm/sB. 0.02 cm/sC. 20 m/sD. 200 m/s |
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Answer» Correct Answer - A `v_("max") = A omega` `= 5 xx 10^(-1) xx 2 pi n = 10 pi (v)/(lamda) xx 10^(-1)` `= (pi xx 0.3 xx 10^(2))/(1.5 pi) = 20 cm//s` |
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| 187. |
A piece of cork is foating on water in a small tank. The cork oscillates up and doen vertically when small ripples pass over the surface of water. The velocity of the ripples being `0.21ms^(-1)`, wavelength 15mm and amplitude 5mm, the maximum velocity of hte piece of cork is A. `0.44ms^(-1)`B. `0.24ms^(-1)`C. `2.4ms^(-1)`D. `4.4ms^(-1)` |
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Answer» Correct Answer - A |
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| 188. |
A string fixed at both ends first oscillates in its fundamental mode then in second harmonic mode.Then match the following. |
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Answer» Correct Answer - (a)P, (b)Q, (c )P |
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| 189. |
In a destructive interference of sound the resultant intensity of sound at a point of medium isA. maximumB. zeroC. minimumD. can not be predicted |
| Answer» Correct Answer - C | |
| 190. |
Wavelengths of two sound notes in air are `(80)/(177)`m and `(80)/(175)m` respectively. Each note of a fixed frequency. What is the velocity of sound in air?A. 300 m/sB. 320 m/sC. 310 m/sD. 350 m/s |
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Answer» Correct Answer - B |
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| 191. |
The similarity between the sound waves and light waves isA. both can pass through vacuumB. both can show interference effectC. both can travel with same speed in mediumD. both are transverse waves |
| Answer» Correct Answer - B | |
| 192. |
The equation of a transverse wave, out the following isA. `X = a sin (Kx - omega t)`B. `Y = a sin (Ky - omega t)`C. `Y = a sin (Kx - omega t)`D. `Z = a cos (Kz - omega t)` |
| Answer» Correct Answer - C | |
| 193. |
The cause of beats is that the two waves undergoA. diffractionB. interferenceC. reflectionD. refraction |
| Answer» Correct Answer - B | |
| 194. |
The prongs of the tuning fork are filed, then the frequency of the tuning fork after filing will beA. increaseB. remain constantC. decreaseD. can not be predicted |
| Answer» Correct Answer - A | |
| 195. |
The maximum number of beats that can be heard per second isA. 5B. 20C. 10D. any number more than 20 |
| Answer» Correct Answer - C | |
| 196. |
Two waves of wavelengths 52.5 cm and 52 cm produces 5 beats per second.their frequencies areA. 490Hz,495 HzB. 500 Hz ,505 HzC. 525 Hz,520 HzD. 500 Hz, 495 Hz |
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Answer» Correct Answer - B |
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| 197. |
When a tuning fork A and B are sounded together,the number of beats heard are 4 per second.When tuning fork A is field,the number of beats heard per second with B is changed to 3.If the frequency of tuning fork B is 384 Hz,the original frequency of A isA. 388 HzB. 387 HzC. 381 HzD. 380 Hz |
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Answer» Correct Answer - D `n_(A) = 300 Hz` `n_(B) = 384 +- 3 = 387 or 381` After filling frequency increases before filling frequency decreases by difference of beat frequency `:. n_(A)= 380` |
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| 198. |
The equation of a progressive wave is, `y = 0.4 sin [pi ((t)/(5) - (x)/(9)) + (pi)/(6)]`, where all quantities are measured in SI units. Then which of the following is correctA. time taken to propagate 1 wave across a point is 10 sB. wavelength is 18 mC. amplitude is 0.4 mD. all the above |
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Answer» Correct Answer - D `omega = (pi)/(5) " " :. 2 pi n = (pi)/(5) " " :. n = (1)/(10)` `k = (2pi)/(lamda)` `(pi)/(9) = (2pi)/(lamda) " " :. lamda= 2 xx 9 = 18 m` `A = 0.4 m` All of the above are correct |
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| 199. |
A bomb explodes on moon. How long does the sound take to reach the earth coverage distance between earth and moon is `3.8 xx 10^(8) m`?A. `1.16 xx 10^(6)s`B. 10sC. `1.16 xx 10^(6)h`D. sound is not transmitted to earth |
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Answer» Correct Answer - D Sound is not transmitted to earth since it requires materail medium |
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| 200. |
Wavelength of wave is a distance between two particles in phase differing byA. `pi `B. ` (pi)/(2)`C. ` 2pi `D. ` (pi)/(4)` |
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Answer» Correct Answer - C |
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