Waves Questions and Answers

Y 4 Sin 400 t and y 3 Sin 404 nt are the equation of displacements of two progressive waves interfering at x 0 The frequency of variation of amplitude at x 0 for the interfered wave will be 1 1 3 3 2 2 4 4

In Young s double slit experiment using the light of wavelength X 60 fringes are seen on a screen If the wavelength of light is decreased by 50 then the number of fringes on the same screen will be 1 30 2 60 3 120

up A standing wave is set up in a string of variable length and tension by a vibrator of variable frequency Both ends of the string are fixed When the vibrator has a frequency f in a string of length L and under tension T n antinodes are set in the string a If the length of the string is doubled by what factor should the frequency be changed so that the same number of antinodes is produced b If the frequency and length are held constant what tension will produce n 1 antinodes c If the frequency is tripled and the length of the string is halved by what factor should the tension be changed so that twice as many antinodes are produced

A wave is propagating along x axis The displacement of particles of the medium in z direction at t 0 P x 2 where x is meters At t 1s the same wave disturbance is given E 2 x Then the wave propagation velocity is given by z exp z exp Option A B C 4 m s in x direction 4 m s in a direction 2 m s in x direction Rate this quest

The figure shows an instantaneous profile of a rope carrying a progressive wave moving from left to right then a the phase at A is greater than the phase at B b the phase at B is greater than the phase at A c A is moving upwards d B is moving upwards y A 1 a c B 2 a d X

1 1 mm 2 0 05 mm 3 0 03 mm 4 0 01 mm In Young s double slit experiment the source is white light One slit is covered with a red filter an other with a blue filter There shall be 1 Alternate red and blue fringes 3 Alternate and yellow fringes 2 Alternate dark and pink fringes 4 No interference

Two sinusoidal waves with same wavelengths and amplitudes travel in opposite directions along a string with a speed 10 ms If the minimum time interval between two instants when the string is flat is 0 5 s the wavelength of the waves is Option A B 25 m C 20 m C 15 m 10 m Rate this question

a 25 Hz c 100 Hz c 100 A band playing music at a frequency u is moving towards a wall at a speed v A motorist is following the band with a speed v If v is the speed of sound the expression for the beat frequency heard by the motorist is a v v v Vb 2v v vm v b 50 Hz d 150 Hz U b d V V v vb 2vm v vy v 16 mu

a 5 6 b 6 5 c 7 4 d 4 7 53 Which of the following statements is incorrect for a stationary wave a Every particle has a fixed amplitude which is different from the amplitude of its nearest particle b All the particles cross their mean position at the same time c All the particles are oscillating with same amplitude d There is no net transfer of energy across any plane

c All the particles are oscillating with same amplitude d There is no net transfer of energy across any plane 4 The fundamental note produced by a closed organ pipe is of frequency u The fundamental note produced by an open organ pipe of same length will be of frequency b u c 20 d 4u 2 65 A steel rod of length 100 cm is clamped at the

A vibrating tuning fork generates a wave given by y 0 1 sint 0 2x 4t where x and y are in meter and time t in second The distance travelled by the wave while the fork completes 20 vibrations is 100 m 120 m 240 m 200 m

Two polaroids are placed at 90 to each other so that the transmitted intensity is zero Find the intensity of the emerging light when a third polaroid is placed between them bisecting the angle between them

An electromagnetic wave going through the vacuum is described by E Eo sin kx wt Which is the following is are independent of the wavelength 1 k 3 kw 2 k w 1 2 2 2 3 2 1 4 2 16

42 180 Longitudinal wave There is no net transfer of energy by the particles of the medium in Transverse wave Progressive wave Mark for Review Stationary wave 02 hr

A plane progressive wave is respresented by the 0 25 cos 2nt 2 x equation y The equation of a wave is with double the amplitude and half frequency but travelling in the opposite direction will be y 0 5 cos t x 1 2 y 0 5 cos 2 t 2x 0 25 cos nt 2 x 3 y 4 y 0 5 cos t x

At t 0 source starts accelerating with an acceleration a and observer starts moving with constant velocity vo as shown in the figure simultaneously Source emits a frequency f and velocity of sound in the air is v The frequency of the initial sound as detected by the observer is v vo f 2vf a A B C D 2 v vo f 2vf a v vo f 2vf a 2 v vo f 2vf 21 source a S l

Waves from two sources superpose on each other at a particular point amplitude and frequency of both the waves are equal The ratio of intensities when both waves reach in the same phase and they reach with the phase difference of 90 will be gut u yon facta for 14 ik nga fch it c y 90 A 1 1 B 2 1 C 2 1 D 4 1 CRI Ki RIER I CI chall

1 13 6eV 2 27 2e V 3 54 4eV 4 68 0e V A pulse of wave train travels along a stretched string and reached the fixed end of the string will be reflected with 1 A phase change of 180 with speed changed 2 The same phase as the incident pulse with no reversal of velocity 3 A phase change of 180 with no change of speed 4 The same phase as the incident pulse but with velocity reversed

A boat at anchor is rocked by waves whose crests are 100m apart and velocity is 25m sec The boat bounces up once in every 1 2500 s 2 75 s 3 4 s 4 0 25 s O p

White light is passed through a double slit and an interference pattern is observed on a screen 2 5 m away The separation between the slits is 0 5 mm The first violet and red fringes are formed 1 mm and 2 5 mm away from the central white fringe Determine the wavelengths of violet and red light A 200 nm 400 nm B 200 nm C 300 nm D 500 nm 400 nm 400 nm 600 nm

Given that a mass of 1 kg is suspended from a spring of stiffness constant 4 N m If the frequency of natural oscillations be 2 3 times the frequency of damped oscil Zations the damping constant is a 5 N m s b 3 N m s c 4 N m s d 2 Nm s O c O b O O a d

frequency 04 A point source of 1 256 Hz and a receiver R are moving along same line with speed u 20 ms towards a reflecting surface which is approaching them with speed u as shown in figure If speed of sound in air is 330 ms then wavelength and frequency of reflected wave received by R are respectively 330 289 61 m and 289 Hz 2140 b 340 289 14 m and 289 Hz

If the optic axes of convex and concave lenses are separated by a distance 5 mm as shown in the figure Find the co ordinates of the final image formed by the combination of lenses if a parallel beam of light is incident on the convex lens Origin is taken at the optical centre of the convex lens and x axis along its optic axis Option A B C D f 20 cm 00 15 mm 30 cm 25 cm 0 5 cm 25 cm 0 25 cm 25 cm 0 5 cm 25 cm 0 25 cm f 10 cm A X Optic axis of concave lens Optic axis of convex lens Rate this questio

4 Two pipes have each of length 2 m One is closed at one end and the other is open at both ends The speed of sound in air is 340 m s The frequency at which both can resonate is a 340 Hz c 42 5 Hz b 510 Hz d None of these

The second harmonic of an open organ pipe of length cm and of radius of cross section 0 5 cm is equal to first overtone of a closed organ pipe of length cm and of same radius of cross section i e 0 5 cm Then which of the following is true 4 0 2 4 3 0 6 c 4 0 4 3 4 0 9

32 A string of length L is stretched by L 20 and speed of transverse wave along it is v The speed of wave when it is stretched by L 10 will be assume that Hooke s law is applicable a 2v c 2 v b 2 d 4 v

2 In a plane progressive harmonic wave particle speed is always less than the wave speed if a amplitude of wave is less than 2 a 2 d amplitude of wave is greater than T b amplitude of wave is greater than c amplitude of wave is less than 2 wavelength of wave

1 The frequency of a sonometer wire is f When the weights producing the tensions are completely immersed in water the frequency becomes 2 and on immersing the weights in a certain liquid the frequency becomes f 3 The specific gravity of the liquid is 4 a 3 b 16 9 c 15 12 d 32 27

35 If 21 2 and 3 are the wavelengths of the waves giving resonance with the fundamental first and second overtones respectively of a closed organ pipe Then the ratio of wavelengths 22 23 is 1 1 a 1 2 3 c 1 3 5 b 1 R 3 5 d 5 3 1

NEET UG 2019 Odisha 3 A tuning fork with frequency 800 Hz produces resonance in a resonance column tube with upper end open and lower end closed by water surface Successive resonance are observed at length 9 75 cm 31 25 cm and 52 75 cm The speed of sound in air is 1 500 m s 3 344 m s 2 156 m s 4 172 m s

How do frequency and wavelength affect the speed of a wave a Increasing wavelength increases the speed but increasing frequency decreases the speed b Increasing wavelength or frequency increases the speed of a wave Oc Increasing frequency increases the speed but increasing wavelength decreases the speed d Changing frequency and wavelength don t affect the speed of a wave

ustration Two loudspeakers as shown in fig below separated by a distance 3 m are in phase Assume that the amplitudes of the sound from the speakers is approximately same at 3m the position of a listener Who is at a distance 4 0 m in front of one of the speakers For what frequencies does the listener hear minimum signal Given that the speed of sound in air is 330 ms A MKIOS 5 4 0m

Two vibrating tuning forks produce progressive waves given by y 4 sin 500xt and y 2 sin 506mt These tuning forks are held near the ear of a person The person will hear a beats s with intensity ratio between maxima and minima equal to Find the value of a Ans

13 A string between x 0 and x vibrates in fundamental mode The amplitude A tension T and mass per unit length is given Find the total energy of the string IIT JEE 2003 Scr x 0 x l sol Sound Wave energy of 1 loop 2 2 1 kaw A here a 21 w 2 f 25 1 I

12 A plane wave given by equation y 0 04 sin 0 5xx 100nt where x and y are in meter and t in sec is incident normally on a boundary between two media beyond which wave speed becomes doubled State boundary condition and find the equation of the reflected and transmitted waves Take x 0 as the boundary between two media soen transmitted wave Ye At Sin K X wt reflected wave Y A Sin x x wt K 8 V 2 1 given A A 2 Ai VI K2 1 1 0 04

Superposition of waves 9 The figure shown a triangular pulse on a rope at t 0 It is approaching a fixed end at 2 cm s a Draw the pulse at t 2 sec b The particle speed on the leading edge at the instant depicted is Sol 6 speed Vpl V x slopel 0 upto 2cm s tano 2cm s 1 2cm s t 2 sec travel 4cm distance point and wave will be inverted A M B2 cm s 2cm 1cm lem 1cm c Wave will point I will react www

50 A taut string for which mass per unit length 5 0 x 10 2 kg m is under tension of 80 N How much power in watt upto one decimal point must be supplied to the string to generate sinusoidal waves at a frequency of 6 0 Hz and amplitude of 6 00 cm a 5 2 W c 2 6 W b 10 4 W d 7 8 W

44 In a stationary wave that forms as a result of reflection of waves from an obstacle the ratio of the amplitude at an antinode to the amplitude at node is n The fraction of energy reflected is n 1 a 2 2 b 2 0 n n 1 n 1 d

A sitar wire is replaced by another wire of same length and material but of triple radius If the tension in the wire remains the same the frequency will become 1 nine times 2 three times 3 one third

d may increase or decrease 23 The equation of a travelling wave is given as y 5 sin 10 t 0 01x along the x axis Here all quantities are in SI units The phase difference between the points separated by a distance of 10 m along x axis is TC b T a 2 cons c 2 d T 4

The linear density of a vibrating string is 1 3 10 4 kg m A transverse wave is propagating on the string and is described by the equation y 0 021 sin x 30t where x and y are measured in meter and t in second the tension in the string is Question Type Single Correct Type 1 0 12 N 2 0 48 N 3 1 20 N

Two identical piano wires kept under the same tension T have a fundamental frequency of 600 Hz The fractional increase in the tension of one of the wires which will lead to occurrence of 6 beats s when both the wires oscillate together would be Question Type Single Correct Type 1 0 01 2 0 02 3 0 03

A tuning fork makes 256 vibrations per second in air When the velocity of sound is 330 m s then wavelength of the tone emitted is Question Type Single Correct Type 1 0 56 m 2 0 89 m 3 A 1 11 m 1 29 m

The satellite orbiting at a height of 359 2 km sends a signal to the surface of the Earth The signal is transmitted by a radio wave that travels at 3 00 x 108 m s The wave s frequency is 5 00 x 1010 Hz What is the wavelength of the radio wave and how long will it take to reach the surface of the Earth

0 If given wave has propagation constant 511 rad m then phase difference between two 7 49 particle having distance difference m is 22 1 5 rad 2 10 rad

In a Young s double slit experiment 12 fringes are observed to be formed in a certain segment of the screen when light of wavelength 600 nm is used If the wavelength of light is changed to 400 nm number of fringes observed in the same segment of the screen is given by 1 12 2 18 3 24 4 30

A travelling wave passes a point of observation At this point the time interval between successive crests is 0 2 seconds and The wavelength is 5 m The frequency is 5 Hz The velocity of propagation is 5 m s The wavelength is 0 2 m

Equation of a progressive wave is given by y 0 2cos 0 04t 02x 0 0 4 cm 8 cm The distance is expressed in cm and time in second What will be the minimum distance between two particles having the phase difference of 2 25 cm 2 12 5 cm 6

20 Figure below shows the distance displacement Compare i the amplitude ii the wavelength of the two waves displacement cm A 10 5 0 0 5 10 2 B 6 graph of two waves A and B 10 12 14 Distance 16

c 73 d 13 16 How long after the beginning of motion is the displacement of a harmonically oscillating point equal to one half of its amplitude if the period is 24 sec and initial phase is zero a 12 sec b 2 sec c 4 sec d 6 sec