InterviewSolution
Saved Bookmarks
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.
| 101. |
A siren emitting a sound of frequency 800 Hz moves away from an observer towards a cliff at a speed of `15ms^-1`. Then the frequency of sound that the observer hears in the echo reflected from the cliff is (Take velocity of sound in air `=330ms^-1`)A. 838 HzB. 885 HzC. 765 HzD. 800 Hz |
|
Answer» Correct Answer - D |
|
| 102. |
A source of sound `S` emitting waves of frequency `100 Hz` and an observer `O` are located at some distance from each other. The source is moving with a speed of `19.4ms^-1` at an angle of `60^(@)` with the source observer line as shown in the figure. The observer is at rest. The apparent frequency observed by the observer (velocity of sound in air `330ms^-1`) isA. 97 HzB. 100 HzC. 103 HzD. 106 Hz |
|
Answer» Correct Answer - D |
|
| 103. |
A distant source of sound has frequency `800` Hz. An observer is facing `90^(@)` away from the direction of the source. Estimate the phase difference between the oscillations of her left and right eardrums. Speed of sound in air `= 340 ms^(–1)`. |
|
Answer» Correct Answer - `16/17 pi` |
|
| 104. |
A source of sound emitting a note of frequency 90 Hz moves towards an observer with speed equal to ` ( (1)/( 10 ) )^(th ) ` of velocity of sound.The frequency of the note heard by the observer will beA. 100 HzB. 82 HzC. 200 HzD. 90 Hz |
|
Answer» Correct Answer - A |
|
| 105. |
Speed of sound wave is v. If a reflector moves towards a stationary source emitting waves of frequency f with speed u, the wavelength of reflected waves will beA. `(v-u)/(v+ u)f`B. `(v+u)/(v)f`C. `(v+u)/(v- u)f`D. `(v-u)/(v)f` |
|
Answer» Correct Answer - C |
|
| 106. |
A policeman blows a whistle with a frequency of 500 Hz.A car approaches him with a velocity of `15 ms^(-1)`.Calculate the change in frequency as heard by the driver of the car as he passes the policeman.Speed of sound in air is `300 ms^(-1)`. |
|
Answer» Correct Answer - 50 Hz |
|
| 107. |
An engine approaches a hill with a constant speed. When it is at a distance of 0.9 km, it blows a whistle whose echo is heard by the driver after 5 seconds. If the speed of sound in air is 330 m/s, then the speed of the engine is :A. 80 m/sB. 30 m/sC. 300 m/sD. 360 m/s |
|
Answer» Correct Answer - B If the speed of the engine is v the distance covered by engine in 5 sec is 5v The distance travelled by sound in reaching in hill and coming back to the moving driver `= 900 + (900 - 5v)` `= 1800 - 5v` Time interval between original sound and echo is `5 = (1800 - 5v)/(330) :. 1800 - 5v = 1650` `:. v = 30 m//s` |
|
| 108. |
A man standing unsymmetrical position between two mountains and fires a gun. He hears the first echo after 1.5 s and the second echo after 2.5 s. If the speed of sound is 340 m/s, then the largest distance between the man and mountain will beA. 340 mB. 410 mC. 425 mD. 255 m |
|
Answer» Correct Answer - C `x_(2) = (vt_(2))/(2)` |
|
| 109. |
A man is driving a car at a speed of 72 kmph towards a hill. He sounds the horn and hears its echo after 2 s. At what distance from the hill the horn was sounded. (Velocity of sound = `340 ms^(-1)`)A. 40 mB. 340 mC. 360 mD. 380 m |
|
Answer» Correct Answer - C `v = 72 xx (5)/(18) = 20 m//s` `v = (2x - 20 xx 2)/(t)` `340 xx 2 = 2x - 40` `680 + 40 = 2x` `2x = 720` `x = 360 m` |
|
| 110. |
A soldier fires a bullet towards a fort-wall and hears the first echo after 2s. He moves a distance of 85m towards the wall, fires a bullet and hears the echo after 1.5 s. The velocity of sound isA. 330 m/sB. 340 m/sC. 345 m/sD. none |
|
Answer» Correct Answer - B `2x = vt_(1) = 2v`...(i) `2x -2 xx 85 = v t_(2) = 1.5 v`...(ii) Subtract equation (ii) from (i), `2 xx 85 = v(2-1.5)` `:. 5v = 2 xx 85` `v = (2 xx 85)/(0.5) = 4 xx 85` `v = 320 m//s` |
|
| 111. |
A man standing between two parallel cliffs fires a gun. If he hears the first echo after 2s and the next after 5s, the distance between the two cliffs is (Velocity of sound in air is 350 m/s)A. 1225 mB. 1050 mC. 2100 mD. 2450 m |
|
Answer» Correct Answer - A `2(x_(1) + x_(2)) = v(t_(1) + t_(2))` `x_(1) + x_(2) = (v)/(2) (t_(1) + t_(1))` `= (350)/(2) (2 + 5)` `= (350 xx 7)/(2) = (2450)/(2) = 1225m` |
|
| 112. |
A man standing at a certain distance blows a horn towards a big wall. He hears the echo after 2s, if the velocity of sound in air is 340 m/s, then the distance between the man and the wall isA. 850 mB. 340 mC. 170 mD. 680 m |
|
Answer» Correct Answer - B `2 x = vt` `:. X = (vt)/(2) = (340 xx 2)/(2) = 340 m` |
|
| 113. |
When a compressible wave is sent towards bottom of sea from a stationary ship it is observed that its echo is hear after `2s`. If bulk modulus of elasticity of water is `2xx10^(9)N//m^(2)`, mean temperature of water is `4^(@)` and mean density of water is `1000kg//m^(3)`, then depth of sea will beA. 707 mB. 1414 mC. 2828 mD. `2000 xx 10^(3) m` |
|
Answer» Correct Answer - B `v = (2x)/(t)` `2x = v t = sqrt((k)/(rho))t` `2x = sqrt((2 xx 10^(9))/(10^(3)) xx 2` `x = sqrt2 xx 10^(3) = 1.414 xx 10^(3)` `x = 1414 m` |
|
| 114. |
A point source of sound is located inside sea water. Bulk modulus of sea water is `B_(omega)=2.0 xx 10^(9) N//m^(2)`. A diver located at a distance of `10` m from the source registers a pressure amplitude of `DeltaP_(0)=3000 pi N//m^(2)` and gives the equation of sound wave as `y=A sin (15 pi x-21000 pit)`, y and x are in meter and `t` is in second. (a) Find the displacement amplitude of the sound wave at the location of the diver. (b) Find the power of the sound source. |
|
Answer» Correct Answer - (a) `0.1 mum` (b) `3.9xx10^(4)` watt |
|
| 115. |
The velocity of sound in alcohol is 1300 m/s and the density of alcohol is 0.08 `g//cm^(3)`. The bulk modulus of alcohol isA. `0.65 xx 10^(-3) N//M^(2)`B. `1.35 xx 10^(3) N//m^(2)`C. `0.65 xx 10^(6) N//m^(2)`D. `1.35 xx 10^(8) N//m^(2)` |
|
Answer» Correct Answer - D `v = sqrt((k)/(rho)) :. V^(2) = (k)/(rho)` `:. k = rhov^(2) = 0.08 xx 10^(+3) xx 1300 xx 1300` `= 1.35 xx 10^(8) N//m^(2)` |
|
| 116. |
The longitudinal waves starting from a ship return from the bottom of the sea to the ship after 2.64 s. If the bulk modulus of water be `220 mm^(-2)` and the density `1.1xx10^(3) kg m^(-3)`.calculate the depth of the sea. Take g =`9.8 N kg^(-1)`. |
|
Answer» Correct Answer - 1848 m |
|
| 117. |
Two waves `y_(1)=a sin (pi/2 x-omegat)` and `y_(2)=a sin (pi/2 x+omegat+pi/3)` get superimposed in the region `x ge 0`. Find the number of nodes in the region `0 le x le 6 m`. |
|
Answer» Correct Answer - `3` |
|
| 118. |
Which two of the following waves are in the same phase? `y= A sin (kx -omega t ) ` ` y=A sin (kx -omega t+pi ) ` ` y= A sin (kx -omegat+ pi //2) ` ` y=A sin (kx -omega t +2pi ) `A. I and IIB. II and IIIC. II and IVD. I and IV |
|
Answer» Correct Answer - D |
|
| 119. |
Assertion: Two equations of wave are `y_(1)=A sin(omegat - kx) and y_(2) A sin(kx - omegat)`. These two waves have a phase difference of `pi`. Reason: They are travelling in opposite directions.A. If both Assertion and Reason are true and the Reason is correct expanation of the Assertion.B. If both Assertion and Reason are true but the Reason is not correct expanation of the Assertion.C. If Assertion is true, but the Reason is false.D. If Assertion is false but the Reason is true. |
|
Answer» Correct Answer - C If both waves `omegat and kx` are opposite signs, then both are travelling in positive directions. |
|
| 120. |
Two waves `y_1 =0.25 sin 316t and y_2 =0.25 sin 310t ` are travelling in same direction .The number of beats produced per second will beA. 6B. 3C. `3//pi`D. `3pi` |
|
Answer» Correct Answer - A |
|
| 121. |
Equations of a stationery and a travelling waves are `y_(1)=a sin kx cos omegat and y_(2)=a sin (omegat-kx)` The phase differences between two between `x_(1)=(pi)/(3k)` and `x_(2)=(3pi)/(2k) are phi_(1) and phi_(2)` respectvely for the two waves. The ratio `(phi_(1))/(phi_(2))`isA. 1B. `(5)/(6)`C. `(3)/(4)`D. `(6)/(7)` |
|
Answer» Correct Answer - D |
|
| 122. |
The displacement of the interfaring light waves are ` y_1 =4 sin omega t and y_2=3sin (omegat +(pi)/( 2)) ` What is the amplitude of the resultant wave?A. 5B. 7C. 1D. 0 |
|
Answer» Correct Answer - A |
|
| 123. |
Two transverse waves travel in a medium in same direction. `y_(1)=a cos (omegat-(2pi)/lambda_(1) x), y_(2)=a cos (2 omegat-(2pi)/lambda_(2) x)` (a) Write the ratio of wavelengths `(lambda_(1)/lambda_(2))` for the two waves. (b) Plot the displacement of the particle at `x = 0` with time (t). |
|
Answer» Correct Answer - (a) `lambda_(1)/lambda_(2)=2/1` |
|
| 124. |
If at `t = 0`, a travelling wave pulse in a string is described by the function, `y = (10)/((x^(2) + 2 ))` Hence, `x and y` are in meter and `t` in second. What will be the wave function representing the pulse at time `t`, if the pulse is propagating along positive x-axix with speed `2 m//s`? |
|
Answer» Correct Answer - A::B Since, wave is travelling along positive x-direction. Hence, coefficient of `t` and coefficient of `x` shouldhave opposite signs. Further, ` v = ("Coefficient of t")/("Coefficient of x")` `:. 2 = ("Coefficient of t")/("Coefficient of x")` :. Coefficient of `t =2` ("coefficient of `x`") `=2 xx1 =SI "units"` `:. y=(10)/((x - 2t)^(2) + 2)` |
|
| 125. |
Equations of two progressive waves at a certain point in a medium are given by, ` y_1 =a_1 sin ( omega t+phi _1) and y_ 1 =a_2 sin (omegat+ phi _2) ` If amplitude and time period of resultant wave formed by the superposition of these two waves is same as that of both the waves,then `phi _ 1-phi _2 ` isA. ` (pi)/(3) `B. ` (2pi)/( 3) `C. ` (pi)/(6) `D. ` (pi)/(4)` |
|
Answer» Correct Answer - B |
|
| 126. |
If at `t = 0`, a travelling wave pulse on a string is described by the function. `y = (6)/(x^(2) + 3)` What will be the waves function representing the pulse at time `t`, if the pulse is propagating along positive x-axis with speed `4m//s`?A. `y=(6)/(x+4t)^(2) +3`B. `y=(6)/(x - 4t)^(2) +3`C. `y =(6)/(x - t)^(2)`D. `y =(6)/(x - t)^(2)+12` |
|
Answer» Correct Answer - B The wave pulse is travelling along positive x-axis. Hence, at and bx should have opposite signs. Further, wave speed `v = ("Coefficient of t")/("Coefficient of x")` `:. 4 = ("Coefficient of t")/(1)` `:. "Coefficient of" `t = 4 s^(-1)` |
|
| 127. |
String-1 is connected with string-2 The mass per unit length in string-1 is ` mu _1` and mass per unit length in string-2 is `4mu _1.` The tension in the strings is T .A travelling wave is coming from the left .What fraction of the energy in the incident wave goes into string-2?A. `(1)/(8)`B. `(4)/(9)`C. ` (2)/(3)`D. ` (8)/(9)` |
|
Answer» Correct Answer - A |
|
| 128. |
A wave pulse is travelling on a string of linear mass density `1.0 g cm^(-1)` under a tension of 1 kg wt. Calculate the time taken by the pulse to travel a distance of 50 cm on the string.Given `g = 10 ms^(-2)`. |
|
Answer» Correct Answer - 0.05 s |
|
| 129. |
A composite wire is made by joining two uniform wires. If `l_1 = l_2= l` and ` mu_1 = mu_2 /9 = mu`. Tension in the strings is T , `mu` is mass per unit length. Then lowest frequency such that the junction is an antinode. A. `(1)/(2l) sqrt(T/mu)`B. `(1)/(l) sqrt(T/mu)`C. `(4)/(l) sqrt(T/mu)`D. `(2)/(l) sqrt(T/mu)` |
|
Answer» Correct Answer - A |
|
| 130. |
A composite string is made up of two uniform strings having mass per units length ` mu ` and ` 4mu ` The string is under uniform surface tension.A transverse wave pulse ` y= 6 sin ( 5t+ 40X) ` where y in mm, x is metres and t is in seconds,is sent through the lighter string towards joints,which is at x=0 The equation of transmitted pulse is,A. `(4mm )sin (5t-40x) `B. `(2mm )sin (40x -5t) `C. ` (4mm ) sin ( 5t+ 40x ) `D. ` (2mm) sin ( 5t-40x)` |
|
Answer» Correct Answer - D |
|
| 131. |
A composite wire is made by joining two uniform wires. If `l_1 = l_2= l` and ` mu_1 = mu_2 /9 = mu`. Tension in the strings is T , `mu` is mass per unit length. Then lowest frequency such that the junction is an antinode. |
|
Answer» Correct Answer - A |
|
| 132. |
The shape of a wave is represented by `y=(1)/(1+x^(2))` at `t=0` and `y=(1)/(1+(x-1)^(2))` at `t=2s`. Assume that the shape of the wave remains unaltered as it advances in the medium. Find the velocity of the wave and represent the wave graphically. |
|
Answer» Correct Answer - `0.5 m//s` |
|
| 133. |
The frequency of transmission of a radio station is 30 MHz. Then the wavelengt of the waves transmitted by the centre will be `(v = 3 xx 10^(8) m//s)`A. 5mB. 10mC. 15 mD. 20 m |
|
Answer» Correct Answer - B `lamda = (v)/(n) = (3 xx 10^(8))/(30 xx 10^(6)) = (300)/(30) = 10 m` |
|
| 134. |
The frequency of waves emitted from a radar is 750 MHz. The frequency of reflected wave from the aeroplane as observed at the radar station is increased by 2.5 KHz. What is the speed of aeroplaneA. `4 Kms^(-1)`B. `2 Kms^(-1)`C. `1 Kms^(-1)`D. `0.5 Kms^(-1)` |
|
Answer» Correct Answer - D `(Deltan)/(n) = (2v_(s))/(v)` `(2.5 xx 10^(3))/(750 xx 10^(6)) = (2 xx v_(s))/(3 xx 10^(8))` `(2.5 xx 10^(3))/(7.5 xx 10^(8)) = (2v_(s))/(3 xx 10^(8))` `2v_(s) = 10^(3)` `v_(s) = (1)/(2) xx 10^(3) = 0.5 km//s` |
|
| 135. |
The whistle of an engine moving at `30km//h` is heard by a motorist driving at `15km//h` and he estimated the pitch to be 500. What would be the actual pitch if two are approaching each other ? Velocity of sound is 1220km//h . |
|
Answer» Correct Answer - 481.8 Hz |
|
| 136. |
When a source of sound moves towards a stationary observer the pitch of sound will appear toA. increaseB. become zeroC. decreaseD. remain the same |
| Answer» Correct Answer - A | |
| 137. |
The Pitch of the whistle of an engine appears to drop to `5/6` th of original value when it passes a stationary observer if the speed of sound in air is 350 m/s then the speed of engine isA. 35 m/sB. 70 m/sC. 105 m/sD. 140 m/s |
|
Answer» Correct Answer - B |
|
| 138. |
When a source moves away from a stationary observer, the frequency is `(6)/(7)` times the original frequency. Given: speed of sound `=330(m)/(s)` . The speed of the source is |
|
Answer» Correct Answer - `55 ms^(-1)` |
|
| 139. |
The number of beats produced per second by two tuning forks when sounded together is 4, If one of them has a frequency of 250 Hz,the frequency of other cannot be more thanA. 246 HzB. 248 HzC. 252 HzD. 254 Hz |
|
Answer» Correct Answer - D |
|
| 140. |
Three tuning forks of frequencies 248 Hz, 250 Hz, 252 Hz, are sounded together.The beat frequency is,A. 2 HzB. 4 HzC. 6 HzD. 8 Hz |
|
Answer» Correct Answer - C |
|
| 141. |
The possible beat frequencies when A and C are sounded together areA. 2 Hz and 7 HZB. 1 Hz and 6 HZC. 1 Hz and 7 HZD. 2 Hz and 6 HZ |
|
Answer» Correct Answer - C |
|
| 142. |
[Q. Nos. 7-8] You have three firks A, B, and C Fork B has a frequency of 440 What A and B are soundedd together a frequency of 3 Hz is heard. When B and C sounded together,the beat frequency is 4 Hz. The possible frequencies of C areA. 437 Hz and 443 HzB. 436 Hz and 444 HzC. 436 Hz and 445 HzD. 437 Hz and 444 Hz |
|
Answer» Correct Answer - B |
|
| 143. |
A stationary observer receiver a sound of frequency `f_(0) = 2000 Hz` .Sourece is moving with constant velocity on a road at some non-zero prependicular distance from observer . The apparent frequncy f varies with times as show in figure . Speed of sound `= 300 m//s`. Choose the correct alternative(s). A. Speed of source is 66.7m/sB. `f_(m)` shown in figure cannot be greather than 2500HzC. Speed of source is 33.33m/sD. `f_(m)` show is figure cannot be greater than 2250 Hz |
|
Answer» Correct Answer - C::D |
|
| 144. |
The equation `y=4 + 2 sin (6t - 3x)` represents a wave motion withA. amplitude 6 unitsB. amplitude 2 unitsC. wave speed 2 unitsD. wave speed `1//2` units |
|
Answer» Correct Answer - B::C |
|
| 145. |
The phenomena arising due to the superposition of waves is/areA. beatsB. stationary wavesC. Lissajous figuresD. All of these |
|
Answer» Correct Answer - D Beats, stationary waves, Lissajous figures all correspond to the phenomena of superposition of waves |
|
| 146. |
Two sound waves of slightly different frequencies propagating in the same direction produce beats due toA. interferenceB. diffractionC. reflectionD. refraction |
|
Answer» Correct Answer - A Beats are produced on account of interference of sound waves of slightly different frequencies |
|
| 147. |
If a stationary observer notes a change of 25% in the frequency of a while of an engine coming towards him then the velocity of the engine is )(velocity of sound =332 m/s )A. 66.4 m/sB. 64 m/sC. 60 km/hrD. 32 km /hr |
|
Answer» Correct Answer - B |
|
| 148. |
`y=3cos 100pi(2t-x)`, the value of `lamda` isA. 4 cmB. 6 cmC. 2 cmD. 1 cm |
|
Answer» Correct Answer - C `y = 3 cos 100 pi (2t - x)` `k = 100 pi` `(2pi)/(lamda) = 100pi` `lamda = (2)/(100) = 0.02 m = 2 cm` |
|
| 149. |
A conveyor belt moves to the right with speed v = 300 m/ min . A pieman puts pies on the belt at a 30 m /min towards a receiver at the other end. The frequency with which they are received by the stationary receiver isA. 26.67 / minB. 30/ minC. 22.22 / minD. 24 / min |
|
Answer» Correct Answer - C |
|
| 150. |
A train is moving with a constant speed along a circular track. The engine of the train emits a sound of frequency f. The frequency heard by the guard at the rear end of the train.A. is less than fB. is greter than fC. is equal to fD. may be greater than , less than or equal to f denpending on the factors like speed of train, legth of train and radius of circular track |
|
Answer» Correct Answer - C |
|