Waves Questions and Answers

is col Q 7 they are exactly out of phase and the interferen 4 A travelling wave at a rigid boundary or a closed end is reflected with a phase reversal but the reflection at an open boundary takes place without any phase change For an incident wave acos wel a cosciutto y x t a sin kx wt the reflected wave at a rigid boundary is y x t a sin kx wt For reflection at an open boundary y x t a sin kx wt 1 2 cos a cos uteg 2 kn wt 2 oring in opposite directions produces standing

1 the wave intensity remains constant for a plane wave 2 the wave intensity decreases as the inverse square of the distance from the source for a spheric wave 3 the wave intensity decreases as the inverse of the distance from a line source total power of the spherical wave over the spherical surface centered at the source remai constant at all the times

In Fraunhoffer diffraction pattern obtained with a single slit at the angular position of first diffraction minimum the phase difference in radian between the wavelets from the opposite edges of slit is a b 2 c TC T T d

instantaneous picture of a longitudinal harmonic wave travelling along the negative x axis Identify the correct statement s related to the movement of the points shown in the figure un vp v d mink YA a A a C f V b C e h g k The points moving in the direction of wave are A b B c C f D i X The points moving opposite to the direction of propagation are B d D j The stationary points are A a C g T B c D k The points of maximum compression are A c B g D k

1 PHYSICS In closed end pipe of length 105 cm standing waves are set up corresponding to the third overtone What distance from the closed end amongst the following is a pressure node 1 20 cm 2 60 cm 3 85 cm 4 45 cm The tension length diameter and density of a string B are double than that of another string A Which fundamental frequency of A the strings are fixed

C 74 In Young s double slit experiment angular width of fringes is 0 20 for sodium light of wavelength 5890 If complete system is dipped in water then angular width of fringes becomes RPET 1997 a 0 11 c 0 22 b 0 15 d 0 30 between

1012 A wave of length 2m is superposed on its reflected wave to form a stationary wave A node is located at x 3m The next node will be located at x 1 3 25 m 2 3 50 m 3 3 75 m 44m

Find the time taken by the particle in going from x 0 to x 2 x Asinot A 2 A sin ot T sin sin 6 TU 2 11 6 T t 2 t t T 12 where A is the amplitude

The linear density of a vibrating string is 1 5x10 kg m The equation of a transverse wave along the string is given by y 0 02 2x 60t where x y are in m and t in s The tension in the string is

Given equation is related to 2 X y cos x cos 2 vt 2 1 Transverse progressive 2 Longitudinal progressive 3 Longitudinal stationary wa 4 Transverse stationary wave

A triangular pulse is moving with speed 2 cm s along a rope kept along x axis whose one end is free at x 0 as shown in the figure Choose the correct option regarding this pulse A B 2cm 0 5cm 2cm x 0 at t 1 sec C Particle speed at t 0 sec is 1 cm s 1cm 2cm X C 2cm 1cm 1cm 2cm x 0 at t 1 sec D Particle speed at t 0 sec is 2 m s

Mark the correct statement s A when a sound wave strikes a wall the compression pulse is reflected as compression pulse B when a sound wave strikes a wall the compression pulse is reflected as rarefaction pulse C when a sound wave is coming out after passing through a narrow pipe then reflection would be there at open end D when a sound wave is coming out after passing through a narrow pipe then compression pulse is reflected as rare fraction pulse

25 The successive frequencies of standing waves setup in an organ pipe are 150 Hz 225 Hz 300 Hz then frequency of 10th harmonics is 1 1500 Hz 2 750 Hz 3 450 Hz 4 600 Hz 31

A string is fixed at a and its free end is at x 0 A triangular shape wave pulse is moving along the string with speed v m s in the positive x axis direction Its position at t 0 is shown in the figure TRENING The shape of wave pulse at t a 2v will be X 0

A broad source of light I 680 nm illuminates normally two glass plates 120 mm long that touch at one end and are separated by a wire 0 034 mm in diameter at the other end incident light 0 034mm 120mm The total number of bright fringes that appear over the 120 mm distance is

Transverse elastic waves can be propagate in 1 Both solid gas 2 In solid but not gas 3 Neither solid nor gas 4 None

lustration 8 A progressive wave having amplitude 5 m and wavelength 3 m If the maximum average velocity of particle in half time period is 5 m s and wave is moving in the positive x direction then find which may be the correct equation s of the wave where x in meter 1 5sin 2 2 x 3 5sin 2x 23 plution 2 4 sin 4 3 cos nt 2n 23 2 5 x 3cos 2t 3 X nt 2n 23 4 sin X 2n 2n 27 X Ans 2 3

x x 51 5 n 4 tan n Which of following can not be polarised 1 Radio waves 2 Ultraviolet rays 3 Infrared rays 4 Ultrasonic waves A polaroid is placed at 45 to an incoming light of intensity I Now the intensity of light passing through polaroid

A 10 m long steel wire has mass of 5 g If wire is under a tension of 80 N the speed of transverse wave on the wire is O 400 ms 1 500 ms 1 O 300 ms 1 O 900 ms 1

The time period of a particle in simple harmonic mo ion is equal to the time between consecutive appearance of the particle at a particular point in its motion This point is 1 the mean position an extreme position 3 between the mean position and the positive extreme 4 between the mean position and the negative

For superposition of two waves in interfe 1 They must have equal frequency and wave length 2 They must have equal frequency but may have unequal wavelengths 3 They must have the same wavelength but may have different frequencies 4 They must have neither equal frequencies nor

4 The displacement produced by a simple harmonic 10 period and maximum velocity of the particle will be wave is y sin 200nt T 17 respectively 1 10 3 second and 200 m s 2 10 2 second and 2000 m s 3 10 3 second and 330 m s 4 10 4 second and 20 m s X cm The time

A wave is represented by y 2 sinn 4t x where x and y are in metres and t is in seconds The wavelength of the wave is 01m 1 2 m Read More 02m

For stationary wave which of the following state ment is correct 1 All the particles vibrate in same phase 2 All the particles between an antinode and node vibrate in phase 3 Particles between any two consecutive nodes vibrate in phase vibrate in different phases

A cylindrical tube closed at one end has a fundamental frequency f in air The th of the tube is filled with water The fundamental frequency of the air column s now 0 Read More 412

2 In YDSE an electron beam is used to obtain interference pattern If speed of electrons is increased 1 No interference pattern will be observed 2 Distance between two consecutive fringes remains same 3 Distance between two consecutive fringes will decrease 4 Distance between two consecutive fringes will A In the fol A is foll 1 2

9 Angular width of principal maximum in single slit diffraction is 0 1 radian Angular width of second order secondary maxima is 10 05 radian 2 0 1 radian 3 0 5 radian

30 The slit in a double slit interference illuminated by a light of wavelength 600 nm A thin transparent sheet of thickness t is placed in front of one of the slits The number of fringe shifting is plotted across the refractive index u of the sheet as given The value of t is N No of fringe shifted 60 50 40 30 20 10 0 25 0 50 0 75 1 00 1 25 1 50 1 75 2 00 1 2 4 m 2 24 m 3 4 8 m

28 In a Young s double slit experiment sources of equal intensities are used Distance between slits is d and wavelength of light used is 2 2 d Angular separation of nearest points on either side of central maximum where intensities become half of the maximum value is 1 2 3 2 2d 2 4d

P A parallel beam of fast moving electrons is incident normally on a narrow slit A fluorescent screen is placed at a large distance from the slit If the speed of the electrons is increased which of the following statements is correct ore NEET 2013 a The angular width of the central maximum of the diffraction pattern will increase b The angular width of the central maximum will decrease The angular width of the central maximum will be unaffected bo d Diffraction pattern is not observed on the c

A particle is vibrating in a simple harmonic motion with an amplitude of 4 cm At what displacement from the equilibrium position is its energy half potential and half kinetic 1 1 cm 2 2 cm 3 3 cm 4 2 2 cm Y K Y cos ot The maximum val

1 white 2 red 3 green The earth radiates in the infra red region of the specturm The spectrum is correctly given by XLRayleigh Jeans law 2 Planck s law of radiation 3 Stefan s law of radiation 4 Wien s law Nouton s law of cooling the rate of cooling of a body is proportional to 40 where 40 i RE

Three waves of equal frequency having amplitude 10 m 4 um and 7 um arrive at a given point with successive phase 7 difference of The amplitude of the resulting wave in um 2 is given by 07 6

0 12 N 2 0 21 N Length of a string tied to two rigid supports is 40 cm Maximum length wavelength in cm of a stationary wave produced on it is 1 20 2 80 3 40 4 120 linear mass density of 9 8 g m is stretched with a tension of 10 kg wt between two rigid supports 1

A travelling wave represented by y A sin ot kx is superimposed on another wave represented by y A sin cot kx The resultant is TAIEEE 2011 1 A wave travelling along x direction 2 A wave travelling along x direction n 3 A standing wave having nodes at x 2 4 A standing wave having nodes at x n 0 1 2 1 5 n 0 1 2

The wire of a sonometer has a length of 1 m and mass 5 x 10 4 kg It has a tension of 20N IF the wire is pulled at a point 25 cm away from one end and released the frequency of its vibrations will be 6 1 2X1 2 150 Hz 3 250 Hz 4 100 Hz 201 6x10 40 27 h 1 200 Hz wova having 3 podes and antipodes is formed between two atoms having a distance of 1 21 between

How many number of maximas are formed on a finite screen in Young s double slit experiment given slit screen separation as 1 meter separation between slits 3 mm and wavelength used is 0 5 mm 05 06 O 11

In a stationary wave all particles are 1 At rest at the same time twice in every period of oscillation 2 At rest at the same time only once in a every period of oscillation 3 Never at rest at the same time 4 Never at rest at all Jocity of

Minimum resonating length of a closed organ pipe is 50 cm when it is vibrated by same frequency then next resonating length will be 1 250 cm 2 200 cm 260 3 150 cm 4 100 cm d frequency is 50 Hz then nath difference will be at the phase differenc

Necessary condicition for interference is that 1 The amplitudes of two waves may differ but the phase difference is constant 2 The amplitudes of two waves are same and the phase difference is constant 3 The amplitudes of two waves are same and the phase difference may change 4 The amplitudes of two waves may differ and the phase difference may vary

In a transverse progressive wave of amplitude A the maximum particle velocity is four times its wave velocity The wavelength of the wave is 4AW BU K k 1 Aw L LIAU TA 4 AW W 4A 23 1 k 4 2 A TA 3 RA

32 7 A wave y 10 sin ax bt is reflected from a dence medium at an origin If 81 of energy is reflected then the equation of reflected wave is 1 y 8 1 sin ax bt y 9 sin ax bt 2 y 8 1 sin ax bt 4 y 10 sin ax bt

Asseertion Water waves in a river are not polarized Reason Water waves are longitudinal as well as transverse in nature 1 If both Assertion Reason are true the Reason is a correct explanation of the Assertion 2 If both Assertion and Reason are true but Reason is not a correct explanation of the Assertion 3 If Assertion is true but the Reason is false 4 If Assertion Reason both are false lected waves is inverted A

There is no net transfer of energy by the particles of the medium in Longitudinal wave Transverse wave Progressive wave Stationary wave

Find the speed of transverse waves in this wire at 10 C Given Young modulus of copper 1 3 x 10 N m Coefficient of linear expansion of copper 1 7 x 10 5 C Density of copper 9 10 kg m Sol V V 11 11 HR T SA Stress S yx Strain S yal P yx XAT m L SxA IIT 1979 Sx volume AT 20 C

Velocity of wave 6 The extension in a string obeying Hooke s law is x The speed of wave in the stretched string is v If the extension in the string is increased to 1 5 x find the new speed of wave V Sol V T E KX u K x u

A plane progressive wave of frequency 25 Hz amplitude 2 5 x 105 m and initial phase zero propagates along the negative x direction with a velocity of 300 m s At any instant the phase difference between the oscillations at two points 6m apart along the line of propagation is and the corresponding amplitude difference is m IIT 1997C s A6 KAX 2 0x 2 5 6 300x1 25 A is amplitude of all particles travelling Same in a wave

Two wires of different densities are joined at x 0 An incident wave Asin K x ot traveling from left to right is partly transmitted and partly reflected from the joint If the wave number in the second string is K2 find the amplitude of the reflected and the transmitted wave Show that a phase difference of occurs in the reflected wave if K K Advanced geometrical understanding of derivative is required Look up Resnick Halliday for hints this question may be above IIT JEE level

1 T T 3 T T 2 T T 4 T 2T 2 The displacements of two particles executing SHM on the same line are given as y asin 2 0 and y bain 2 0 phase difference between them at f 1 sis 1 2 EN The

When a stretched string of length L is vibrating in a particular mode the distance between two nodes on the string is I The sound produced in this mode of vibration constitutes the nth overtone of the fundamental frequency of the string Then L n 1 L n 1 L nl L n