Waves Questions and Answers

24 A uniform string is clamped at its two ends Its mass per length is given by 20 g m the transverse displacement wave of the string is given by y 5 sin string is 1 9 N 3 1 8 N 2 3 xco cos 20nt m then tension in the x 2 0 9 N 4 18 N

A uniform rod of length L is free at one end x L and is subjected to a sinusoidal displacement S S sin ot at the other end x 0 As a result each point on the rod oscillates with same frequency o but with different amplitude Here Y represents Young s modulus and p is density of the rod Normally the motion will be damped and the amplitude will be less than the values predicted But here we will be ignoring this effect Using these conditions x 0 The displacement s at x t is given by x L

Sir what s quick approach of this one B A sinusoidal travelling wave of wavelength propagates along positive x axis Three particles 1 2 and 3 in a medium are such that 1 and 2 always have same speed while 1 and 3 always have same velocity The minimum distance between particles 1 1 and 2 is 4 3 1 and 3 is 2 2 and 3 is 4 1 and 2 is 3

3 A transverse wave of frequency 250 Hz produced in a stretched string is shown in the figure Displacement of particles 5 cm 5 cm 1 cm 3 teen from 3 cm 5 cm Length of string The velocity of wave will be 1 10 m s 3 15 m s 2 20 m s 4 40 m s

The horizontal sweep oscillator frequency vertical sweep circuit frequency and the pectrum bandwidth of a 625 line TV system are respectively 50Hz 15625Hz and 7MHz 7MHz 50Hz and 15625Hz 15625Hz 50Hz and 7MHz 15625Hz 7MHz and 50Hz

A stretched string has a mass per unit length of 6 27 g cm and a tension of 16 8 N A sinusoidal wave on this string has an amplitude of 0 147 mm and a frequency of 117 Hz and is traveling in the negative direction of an x axis If the wave equation is of the form y x t ym sin kx wt what are a ym b k and c w and d the correct choice of sign in front of w a Number b Number c Number Mi Mi Units Units Units

A transverse wave of frequency 250 Hz produced in a stretched string is shown in the figure Displacement of particles 5 cm 5 cm The velocity of wave will be 10 m s 20 m s Af 1 cm 3 cm 5 cm Length of string 15 m s 40 m s

A plane sound wave is generated in a medium along the x axis whose equation is given by y A cos ot kx If c is speed of wave in the medium there is a reference frame S which is moving with uniform acceleration a in ve direction of x axis at t 0 both wave and reference frame S coincide with each other at origin The equation of wave in reference wave S is A y Acos at 1 B y Asin ot 1 at 2c at 2c y Asin oot kx kx at C y Acos eot 1 21 kx 2c not 1 at kx

A rod of specific gravity 0 7 is found to be stretched by one millimetre when suspended vertically and loaded with a weight of lead of specific gravity 11 the volume of the weight being equal to that of the rod What fundamental approximately frequency will the rod alone emit when clamped at the middle and rubbed longitudinally A 1 1100g 2 7 B 11x10 g 7 C 770g 2 3 D 1 2 7 10 g 11

object to the image is 28 cm A point is 35 cm along the optical axis from a spherical concave mirror having a focal length 25 cm At what distance along the optical axis from the concave mirror should a plane mirror be placed for the image it forms to coincide with the point source

In a biprism experiment by using light of wavelength 5000 5 mm wide fringes are obtained on a screen 1 0 m away RPMT 2009 from the coherent sources The separation between the two current sources is 2 0 1 mm 3 0 05 mm 1 1 0 mm 4 0 01 mm Monochromatic light of frequency 5 x 10 4 Hz travelling in vacuum enters medium of refractive index 1 5 Its wave IPPMT 20091

In YDSE the separation d between the slits is 2 mm the wavelength of the light used is 5896 and distance D between the screen and slits is 100 cm It is found that the angular width of the fringes is 0 20 with same A and D the separation between the slits needs to be changed to NEET 2018 1 1 8 mm 2 1 9 mm 3 2 1 mm 4 1 7 mm

3 Nature is quantum 4 Nature of light is tranverse In an experiment the two slits are 0 5 mm apart and the fringes are observed to 100 cm from the plane of the slits distance of the 11th bright fringe from the Ist bright fringe is 9 72 mm Calculate the wavelength 1 4 86 x 10 5 cm 2 4 86 x 10 8 cm 3 4 86 x 10 6 cm 4 4 86 x 10 7 cm

5 20 cm a Find the amplitude b Find the wavelength cm c Find the period cm d Find the speed of the wave m s Need Help 1 Points Need Help Read It DETAILS SERCP11 13 9 P 051 A piano string having a mass per unit length equal to 5 10 x 10 kg m is under a tension of 1 400 N Find the speed with which a wave travels on this string m s Read It MY NOTES ASK YOUR TEACHER Watch it PRACTICE ANOTHER 2 Points DETAILS SERCP11 14 3 OP 008 MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER On a bright winter s day a student notices an echo as he walks between a high school s playing field and the rear wall of its auditorium He decides to estimate how far he stands from the reflective wall He abruptly claps and determines that the sound pulse returns to his as an echo 0 492 seconds later averaging several trials for enhanced reliability The air is a frigid 10 C

A string is attached vertically from one end to a vibrator and from the other end to a block of mass m 1 8 kg The power delivered to produce a wave on this string is P 10 W Assume that the block is replaced by a lighter one with a mass m 0 45 kg Determine the new power P required to generate a wave with the same amplitude and frequency

When a wave gets refracted in to a denser medium then which of the following property of wave remains unchanged Speed Wavelength sec O Frequency

A transverse wave propagating on the string can be described by the equation y 2sin 10x 300t where x and y are in metres and t in second If the vibrating string has linear density of 0 6 x 10 3 g cm then the tension in the string is 1 5 4 N 2 0 054 N 4 0 0054 N 42 10

One end of a wire is connected to the wave generator ond the other end is connected to a 215 g mass poesed through a spool When the contact point on the reel and the wave generator connected to the other end of the wire is subjected to a frequency of 120 Hz R creates a standing wave with two nodes on the wire the wove generator ends on the reel to which the wire is connected and the wave generator ends will not be considered What masses must be attoched to the end of the wire to create one and four stoble knots on the wire Compose the answer to the question by drawing and showing one and four knot points on the wire

In a Young s double slit experiment the slits are separated by 0 38 mm and the screen is placed 1 5 m away The distance between the central bright fringe and the fourth order bright fringe is measured be 1 4 cm Wavelength of the light used in the experiment is 3355 9977 8866 1466

Length of resonance tube is 140 cm How many resonance are possible for wave have wave length cm Length of resonance tube is 150 cm How many resonance are possible for wave having frequen 400 Hz and speed of sound 320 m s Length of resonance tube is 150 cm Maximum level of liquid in resonance candition for wave hav wavelength 80 cm is Length of resonance tube is 150 cm Minimum level of liquid in resonance candition for wave hav wavelength 80 cm is

Two identical wires tied at both the ends under the same tension are oscillating in resonance Find the fractional change in tension of one of the wires to produce 5 beats per second a 0 1 b 0 2 c 0 01 d 0 02

If the fundamental frequency of a closed organ pipe is 110 Hz If it produces 2 2 Hz bea with an open organ pipe vibrating in the first overtone when the closed organ pipe is also oscillating in first overtone Find the lengths of the pipes a 0 75m 1 006m c 0 5m 1 003m b 0 50m 1 00m d 0 75m 1 004m

5 A tuning fork having a frequency of 340 Hz is vibrated just above a resonance tube The height of the tube is 120cm Water is slowly poured in it Find the minimum height of water required for resonance given speed of sound in air is 340m s b 45cm c 100cm a 75cm d Not possible

A two conductor transmission line is 10 cm long A sinusoidal signal of 1V peak amplitude is applied to one end of the line If the signal travels on the line with a speed of 2 x 108 m sec find a transit time on the line b frequency at which the transit time is 10 of the signal period c signal voltage on the other end of the line at an instant when the input signal is passing through ve maximum for a frequency of 500 MHz

A small block of mass m is placed on a platform that has a rectangular protrusion The block is connected to one end of a light inextensible cord that passes over an ideal pulley fixed on the corner of the rectangular protrusion and final y attached to the wall Segment of the cord between the pulley and the wall is horizontal and is at a height h above the top face of the platform as shown in the figure The platform is on a horizontal frictionless floor Coefficient of friction between the block and top face of platform is 4 The platform is pulled away from the wall so that it moves with a constant velocity D Find the force F pulling the platform when segment of the cord between the block and the pulley makes angle with the horizontal Denote acceleration of free fall by g and assume that the block does not leave the platform

A string is stretched between fixed points departed by 75 cm It is observed to have resonant frequencies of 420 Hz and 315 Hz There are no other resonant frequencies between these two Then the lowest resonant frequency for this string is a 105 Hz b 1 05 Hz d 10 5 Hz c 1050 Hz AIEEE 2006

emits most of its light at a wavelength of 500 nm What wavelengt at the Earth if the star is receding at half the speed of light

nmax A stationary observer receives a sound from 1000 Hz a sound of frequency fo n Hz moving with a constant velocity v 30 m s The apparent frequency varies with time as shown in figure Velocity of sound v 300 m s Then which of the following is incorrect nmin 2 a The minimum value of apparent frequency is 889 Hz b The natural frequency of source is 1000 Hz c The frequency time curve corresponds to a source moving at an angle to the stationary observer d The maximum value of apparent frequency is 1111H

Two strings AB and BC of length 1 meter and 1 2 meter respectively are joined together at end B as shown Point B is the junction of both strings The mass per unit length of string AB and BC are 0 16 kg m and 0 25 kg m respectively A tension of 100 N is maintained in both the strings A sinusoidal wave pulse of amplitude 2mm is produced at end A It is partly reflected and partly transmitted at joint B A At A B C

37 A body oscillates with SHM according to the equation x 5 0 os 2 t r At time t 1 5 s its displacement speed and acceleration respectively is 1 0 10 20 3 2 5 20 0 2 5 0 20 4 5 0 5 10

35 Equation of motion in the same direction is given by y A sin t kx y2 A sin t kx 0 The amplitude of the medium particle will be b 2A cos 0 a 2A cos 0 2 c 2A cos 0 d 1 2f 1 22

28 A boy is walking away from a wall at a speed of 1 0 ms in a direction at right angles to the wall The boy blows a whistle steadily An observer towards whom the boy is moving hears 4 beats s If the speed of sound is 340 ms the frequency of whistle is a 480 Hz b 680 Hz c 840 Hz d 1000 Hz Observer Box Wall

36 Two pulses travel in mutually opposite directions in a string with a speed of 2 5 cm s as shown in the figure Initially the pulses are 10 cm apart What will be the state of the string after two seconds a 10 cm b d 10 cm

A string under a tension of 100 N emitting its fundamental mode gives 5 beats s with a tuning fork When the tension is increased to 121 N again 5 beats s are heard The frequency of the fork is a 105 Hz c 210 Hz b 95 Hz d 190 Hz

O Question No 4 O Each Question has FOUR options A B C and D ONLY ONE of these four options is correct O Marking Scheme FULL MARKS 3 Only if the alphabet corresponding to the correct option is selected ZERO MARKS if none of the alphabets is selected NEGATIVE MARKS 1 in all other cases 8 7 Two coherent sources S and S emitting light of wavelength 2 are placed in distance D as shown The total number of minima on the screen is S 37 S Answered D Not Visited Not Answer Marked O for Review Answered Marked f Review will be considered for evaluation hy Sec 1 hoose a Question 1234

Question Paper Section Wise IV or the correct numerical value using the ne onscreen virtual numeric keypad 1 will be awarded according to the following correct numerical value is entered as other cases Sections Time Left 151 39 Keypad Backspace 0 Ans 5 Not Visit 0 Ans Rev erference experiment one slit happens to have its width 4 times that of the sity of out coming light is proportional to slit width the ratio of the maximum Phy e interference pattern is cons eval Cho Que 161 20

The amplitude of two waves whose resultant is a standing wave is A Find the amplitude of oscillation of the medium particles located at a distance from the node where is the wavelength of the individual waves 1 A 3 3 A 2 2 A 4 A

Two vibrating strings of the same material but of lengths L and 2L have radii 2r and r respectively They are stretched under the same tension Both the strings vibrate in their fundamental modes The one of length L with frequency f and the other with frequency f The ratio 1 2 3 8 1 12 is is given by 3 4 4 1

A string of length L 1 meter mass 10 gram is tied between two rigid walls The string is sustaining a standing wave and tension in string is T 100 N String is vibrating in 2nd overtone and at t 0 string is flat Amplitude of string particles at antinode points is 2 cm n 10 Amplitude of oscillation in cm of a particle lying at x L 4 is

A car traveling at 25 m s is approaching a stationary wall Wind is blowing in a direction opposite to car at 5 m s At an instant the car driver briefly blows the horn He heard an echo 11 exactly 3 seconds later after sounding the horn and notes that its frequency is 156 Hz Take speed of sound 330 m s At what distance in m from the wall the driver blows the horn

2 The figure below is a representation of a simple harmonic YA progressive wave progressing in the negative X axis at a given instant The direction of the velocity of the particle at stage P in the figure is best represented by the arrow a PA c PC Displacement b PB d PD A B X

A sout horizontally to the right It is reflected from a large vertical plane surface moving to the left with a speed v The speed of sound in the medium is e then study following statements 1 The frequency of the reflected wave is f c v C v i The wavelength of the reflected wave is i The number of waves striking the surface per second f c v is c c v f c v iv The number of beats heard by a stationary listener to fv the left of the reflecting surface is Correct statements are a i ii and iii c ii iii and iv b i ii and iv d i iii and iv

A transverse wave on a string travelling along ve x axis has been shown in the figure below VAA The mathematical form of the shown wave is 2 y 3 0 cm sin 2x 0 1t X 100 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 4 A source of sound S is travelling at 100 3 m s along a road towards a point A When the source is 3 m away from A a person standing at a point O on a road perpendicular to AS hears a sound of frequency The distance of O from A at that time is 4 m If the original frequency is 640 Hz then the value off is velocity of sound is 340 m s a 620 Hz b 680 Hz c 720 Hz d 840 Hz 0 100 3m 3 4 m ms

A plane progressive wave of frequency 50Hz travelling along positive x axis is represented as y 5 x 10 5 m sin 1007t at x 0 Wave speed is 300 m s What is maximum difference in displacements from mean position at x 0 and x 3 m

propagating along x axis then its velocity will b x and y in meters and t in sec 1 A WIN N W N W 3 m s along ve x axis 2 322 m s along ve x axis m s along ve x axis

9 A uniform string of length L is suspended from a point on ceiling A small wave pulse is now introduced at its lowest end and start moving up towards ceiling The acceleration of the moving pulse will be 1 10m s2 3 6m s2 25m s2 4 8m s2

Both the strings shown in the figure are made of same material and have same cross section The pulley is light The wave speed of a transverse wave in the string AB is v and in CD it is v Then v v 1 is 1 1 3 2 11 B A TTHITT D 2 2 1 4 2

An observer approaches a stationary source with speed v Which of the following correctly represents the variation of fractional change in observed frequency with speed of observer 1 3 Af f Af f V 2 4 Af f Af f V

An object undergoing SHM takes 0 5 s to travel from on point of zero velocity to the next such point The distanc between those points is 50 cm The period frequency and amplitude of the motion is a 1s 1Hz 25 cm c 1s 2Hz 25 cm b 2s 1Hz 50 cm d 2s 2Hz 50 cm