InterviewSolution

Explore topic-wise InterviewSolutions in .

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.	The prong of an electrically operated tuning fork is connected to a long string of `mu=1 kg//m` and tension 25 N, the maximum velocity of the prong is `1 cm//s`, then the average power needed to drive the prong is A. `5xx10^(-4) W`B. `2.5xx10^(-4)W`C. `1xx10^(-4)W`D. `10^(-3)W`
Answer» Correct Answer - b Wave velocity: `v=sqrt((F)/(mu))=sqrt((25)/(1))=5 m//s` Average power: `p_(av)=(1)/(2)muv(omegaA)^(2)` `=(1)/(2)muv(v_(p-max))^(2)=(1)/(2)xx1xx5(1xx10^(-2))^(2)` `=2.5xx10^(-4) W`

152.	A string of length `L` fixed at its at its both ends is vibrating in its `1^(st)` overtone mode. Consider two elements of the string of same small length at position `l_1=0.2L` and `l_2=0.45L` from one end. If `K_1` and `K_2` are their respective maximum kinetic energies thenA. `K_(1) = K_(2)`B. `K_(1) gt K_(2)`C. `K_(1) lt K_(2)`,D. It is not possible to decide the relation.
Answer» Correct Answer - B

153.	`y_(t)=2sin3pit` `y_(2)=2sin(3pit-(pi)/(8))` In the above question, the displacement of particle at `t=1 sec` and `x=4cm` isA. 4cmB. 2cmC. 1cmD. zero
Answer» Correct Answer - b

154.	`y_(t)=2sin3pit` `y_(2)=2sin(3pit-(pi)/(8))` The wave velocity isA. `16cm//sec`B. `24cm//sec`C. `12cm//sec`D. `8cm//sec`
Answer» Correct Answer - b

155.	The rope shown at an instant is carrying a wave travelling towards right, created by a source vibrating at a frequency n . Consider the following statements I. The speed of the wave is `4n xx ab` II. The medium at a will be in the same phase as d after `(4)/(3n)s` III. The phase difference between b and e is `(3pi)/(2)` Which of these statements are correctA. The speed of the wave is `4nxxab`B. The medium at a will be in the same phase as d after `(4)/(3n)s`C. The phase difference between b and e is `(3pi)/(2)`D. The speed of the wave is `2nxxab`
Answer» Correct Answer - a, c

156.	`y-x` curve at an instant for a wave travelling along `x-`axis on a string is shown. Slope at the point `A` on the curve, as shown, is `tan 53^(@)`. A. Transerse velocity of the particle at point A is positive if the wave is travelling along positive x axisB. transverse velocity of the particle a t point A positive if the wave is travelling along negative x axis of the particle at point AC. Magnitude of transverse velocity of the particle at point A is greater then wave speedD. Magnitude of transverse velocity on a string of the particle at point A is lesser then wave speed
Answer» Correct Answer - B::C

157.	A transverse waves is travelling in a string. Study following statement. (i) Equation of the wave is equal to the shape of the string at an instant t. (ii) Equation of thhe wave is general equation for displacement of a particle of the string (iii) Equation of the wave must be sinusoidal equation (iv) Equation of the wave is an equation for displacement of the particle at one end only.correct statement areA. (i) and (ii)B. (ii) and (iii)C. (i) and (iii)D. (ii) and (iv)
Answer» Correct Answer - a At any instant `t`, the wave equation will express the variation of `y` with `x` which is equal to the shape of the string at an instant `t`.

158.	A 4.0 kg block is suspended from the ceiling of an elevator through a string having a linear mass desity of `19.2xx10^-3 kgm^-1`. Find the speed (with respect to the string) with which a wave pulse can proceed on the string if the elavator accelerates up at the rate of `2.0ms^-2. Take g=10 ms^-2`.
Answer» `mu=19.2xx10^(-3)kg//m` from the free body diagram `T-4g-4a=0` `T=4(a+g)=4(2+10)=48N` wave speed: `v=sqrt((T)/(mu))=sqrt((48)/(19.2xx10^(-3)))=50 m//s` `so n=4`

159.	A plane wave is represented by `x=1.2 sin (3 14 t + 12.56 y)` Where x and y are distances measured along in x and y direction in meters and t is time in seconds. This wave has
Answer» Correct Answer - A wavelength of `0.5m` and travels in -ve y direction

160.	The equation of a trevelling wave In a uniform string of mass per unit length unit length `mu` is given as `y=Asin(omega-kx)`.Find the total energy transferred through the origin in time interval from t = 0 to `t=pi//12omega.`(You can use the formula in instantaneous power if you know)
Answer» Correct Answer - `((pi+3)/(24)(muomega^(2)A^(2))/(k))`

161.	The equation to a transverse wave travelling in a rope is given by `y=A cos(pi)/(2)[kx-omega-alpha]` where `A=0.6 m, k=0.005 cm^(-1),omega=8.0 s^(-1) and `alpha` is a non-vanishing constant. Then for this wave,A. the wavelength of the wave is `lambda=8m`B. the maximum velocity `v_(m)` of a particle of the rope will be, `v_(m)=7.53 m//s`.C. the equation of a wave which, when superposed with the given wave can produce standing waves in the rope is `y=A cos(pi)/(2)(kx+omega-alpha)`D. The equation of the wave can be represented by `y 2a cos(v)/(a)[t+(x)/(V)]`
Answer» Correct Answer - a.,b.,d. Given wave is `y=A cos.(pi)/(2)[kx-omega-alpha]` here wave number, `kxx(pi)/(2)=(2pi)/(lambda)` giving `lambda=(4)/(k)` here `k=0.005 cm^(-1)`. Hence `lambda=(4)/(0.005)cm=8m` maximum velocity `V_(m)=Axx` angular velocity. Here angular velocity `=(piomega)/(2)=(3.14xx8)/(2)=12.56 rad//s` hence `V_(m)=0.6xx12.56 m//s=7.53 m//s` Also, to produce stationary waves, the two waves should travel in opposite direction and have same frequency. the wave given by `y=A cos(pi)/(2)(kx+omegat-alpha)` fulfils this condition.

162.	Consider a wave rpresented by `y= a cos^(2) (omega t-kx)` where symbols have their usual meanings. This wave hasA. an amplitude `a`, frequency `omega`, and wavelength `lambda`.B. an amplitude `a`, frequency `2omega`, and wabvelength `2lambda`.C. an amplitude `a//2` frequency `2omega` and wavelength `lambda//2`.D. am amplitude `a//2` frequency `2omega`, and wavelength `lambda`.
Answer» Correct Answer - c `y=a[(1+cos(2omegat-2kx))/(2)]` `y=(a)/(2)+(a)/(2)cos(2omegat-2kx)`

163.	The path difference between the two waves `y_(1)=a_(1) sin(omega t-(2pi x)/(lambda)) and y(2)=a_(2) cos(omega t-(2pi x)/(lambda)+phi)` isA. `(lambda)/(2pi)/phi`B. `(lambda)/(2pi)(phi+(pi)/(2))`C. `(2pi)/(lambda)(phi-(pi)/(2))`D. `(2pi)/(lambda)(phi)`
Answer» Correct Answer - b `y_(1)=a_(1)sin(omegat-(2pix)/(lambda))` `y_(2)=a_(2) sin(omegat-(2pix)/(lambda)+phi+(pi)/(2))` phase difference `=(omegat-(2pix)/(lambda)+phi+(pi)/(2))-(omegat-(2pix)/(lambda))=(phi+(pi)/(2))` path difference `=(lambda)/(2pi)xx`phase differance` =(lambda)/(2pi)(phi+(pi)/(2))`

164.	An observer standing at the sea coast observes `54 waves` reaching the coast per minute. If the wavelength of a wave is `10 m`, find the wave velocity.A. `19 m//sec`B. `29 m//sec`C. `9 m//sec`D. `39 m//sec`
Answer» Correct Answer - C

165.	Shows a snapshot of a sinusoidal travelling wave taken at `t=0.3s`. The wavelength is 7.5 cm and amplitude is 2 cm. if the crest P was at x=0 at t=0, write the equation of travelling wave.
Answer» Given ,`A=2 cm,lambda=7.5 cm` `k=(2pi)/(lambda)=(4pi)/(15)cm^(-1)` The wave has travelled a distance of `1.2 cm` in `0.3 s`. hence, speed of the wave, `v=1.2//0.3=4 cm//s` Therefore, angular frequency `omega=(v)(k)` `=(16pi)/(15) rad//s` Since the wave is travelling along positive `x-`direction and crest (maximum displacement) is at `x=0` at `t=0`, we can write the wave equation as, `y(x,t)=2 cos (kx-omegat)` `=2 cos((4pi)/(15)x-(16pi)/(15)t)`

166.	A transverse wave on a string travelling along + ve x-axis has been shown in the figure below: The mathmetical form of the shown wave is `y=(3.0 cm) sin [2pixx0.1t-(2pi)/(100)x]` where t is in seconds and x is in centimetres. Find the total distance travelled by the particle at (1) in 10 min 15 s. measured from the instant shown in the figure and direction of its motion at the end of this time. A. 6 cm, in upward directionB. 6 cm, in downward directiionC. 738 cm, in upward directionD. 732 cm, in upward direction
Answer» Correct Answer - c At the moment shown in the figure, particle at `1` is moving in the downward direction. we have, `T=1//0.1 s=10 s`. in one complete cycle, particle travels a distance, `4` times the amplitude. So, in time `10` min `10 s`, i.e., `615 s` which means 61 full `+ 1` half cycles, hte distance travelled `=(4xx3)xx61+(2xx3)xx1=732+6=738 cm` At time instant, the particle is moving in the upward direction.

167.	Mark out the correct statement(s) concerning waves.A. A wave can have both transverse and longitudinal components.B. A wave does not rejult in the bulk flow of the materials of its medium.C. A wave is a travelling disturbance.D. A wave can be there even in the absence of an elastic medium.
Answer» Correct Answer - a., b., c., d. The statement (a) is supported by water waves. An elastic medium is required for mechanical waves only. So, option (b) and (c ) are also correct.

168.	Mark out the correct statement (S) e.r.t. wave speed and particle velocity for a transverse travelling mechanical wave on a string.A. The wave speed is same for the entire wave, while particle velocity is different for different points at a particular instant.B. wave speed depends upon property of the medium but not on the wave properties.C. wave speed depends upon both the properties of the medium and on the properties of wavesD. particle velocity depends upon properties of the wave and not on medium properties.
Answer» Correct Answer - a., b., d. it is a know fact as well as experimentally and analytically verified that wave speed depends on the properties of the medium and is same for the entire wave. The particle velocity is given by `v_(p)=(dely)/(delt)=-Aomega `cos(kx-omegat)` where symbole have their usual meanings. it is clear from above expression that `v_(p)` depends upon amplitude and frequency of wave which are wave properties and are having different value for different particle at a particular instant.

169.	A harmonic wave is travelling along +ve x-axis, on a stretched string. If wavelength of the wave gets doubled, thenA. frequency of wave may changeB. wave speed may changeC. both frequency and speed of wave may changeD. only frequency will change
Answer» Correct Answer - a., b., c.,d. Wavelength of a wave is a property of source and mediumm both. So, wavelength can change if either frequency of speed of wave or both change. Here, medium property (like tension in string ) can change freq. may change which causes the change in the speed of wave, or source frequency may change.

‹ 1 2 3 4 ›