Waves Questions and Answers

A 10 m long steel wire has mass of 5 g This wire is under a tension of 80 N The speed of transverse wave travelling on it is 200 ms 1 300 ms 1 340 ms 1 hr m 400 ms 1

ind 2 30 5 cm OOP A tube 1 m long is closed at one end A stretched wire is placed near the open end The wire is 0 3m long and has a mass of 0 01kg It is held fixed at both ends and vibrates in its fundamental mode It sets the air column in the tube into vibration at its fundamental frequency by resonance Find a the frequency of oscillation of the air column b the tension in the wire If speed of sound in air is 330 m s mont if Y 300 m s n 500 Hz L 125 cm

27 A sonometer wire is to be divided into three segments having fundamental frequency in the ratic 1 23 the ratio of lengths should be 2 4 3 1 4 6 3 2 1 3 2 1 3 4 2 3

Two tuning forks A and B produce 4 beats per second The fork A is in resonance with a 30cm length of sonometer wire and B is in unison with 25cm of the same wire at same tension The frequency of the forks A and B respectively is a 20Hz 24 Hz b 24 Hz 20 Hz c 25 Hz 20 Hz d none

Explain the phenomenon of beats An ambulance blowing a siren of frequency 700 Hz is travelling towards a vertical reflecting wall with a speed 7 2 km h 1 Calculate the number of beats heard in one second by the driver of the ambulance Take speed of sound as 340 ms

Waves from two different sources overlap near a particular point The amplitude and the frequency of the two waves are same the ratio of the intensity when the two waves arrive 90 out phase to that when they arrive in phase is 1 1 1 3 1 2 2 1 2 4 1 4

cut each double heli ugar phosph predictably sequences th c That is t dentical bas pe of natur 1 A tuning fork is used to produce resonance in a glass tube The length of the air column in this tube can be adjusted by a variable piston At room temperature of 27 C two successive resonances are produced at 20 cm and 73 cm of column length If the frequency of the tuning fork is 320 Hz the velocity of sound in air at 27 is 1 330m s onito 2 339 m s 4 350 m s

Changing frequency of a Sonometer Wire A straight sonometer wire is stretched by the weight of a solid hanging block When oscillating the complete wire its oscillating frequency is n When block is immersed in water its frequency is n and when immersed in a liquid its frequency becomes n Find the specific gravity of block and tha of liquid

2 The transition from the state n 3 to n 1 in a hydrogen like atom results in ultraviolet radiation Infrared radiation will be obtained in the transition from a 21 c 4 2 b 32 d 43 Mains 2012

If the wire is gently tapped in vertical direction halfway between the pulleys what is the lowest frequency at which it will vibrate transversely The mass per unit length of the eire is 0 02 kg m and it has a length of0 2 m between pulleys Volume of block is 1 4 200 3 m and its mass is 10kg Water

Two identical flutes produce fundamental notes of frequency 300 Hz at 27 C If the temperature of air in one flute is increased to 31 C the number of beats heard per second will be A B 1 2 3 C Correct Answer

In YDSE 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 the number of fringes observed in the same segment of the screen is given by 12 18 24 O 30

The speed of electromagnetic wave in a medium of dielectric constant 2 25 and relative permeability 4 is approximately Only one correct answer A 1x 108 m s B 2 5 x 108 m s C 3 x 108 m s C 2108mila i

Dispersion of light in a medium implies that Light of different wavelengths travel with equal speed in medium Light of different frequencies travel with equal speed in medium Refractive index of medium is different for different wavelengths

Two identical progressive waves moving in opposite direction superimpose to produce a stationary wave The wavelength of each progressive wave is X The wavelength of the stationary wave is A B C 4 NIX 2

A string of mass 0 1 kg is under a tension 1 6 N The length of the string is 1m A transverse wave starts from one end of the string The time taken by the wave to reach the other end is 0 30 s 0 50 s A B C D 0 25 s 0 75 s

The transverse stationary wave on a stretc wire Clamped at its both ends is given y x t 0 06 sin x cos 120nt 2A 3 where x and y are in m and t in second length of string is 1 5 m and it s mas 3 x 10 kg then all the points on the w vibrate with 1 Same phase 3 Same energy f 237 2 Same amplitu 4 Different freque

A wave travelling along a string is describ by y x t 0 005 sin 20nt 10 x 2 where x is in cm and t is in sec Calculate displacement y of the wave at a dista x 1 cm and time t 1 sec 1 y 0 0025 cm 2 y 0 0025 cm 3 y 0 005 cm

3 10 The wavelength of a standing wave in a 40 cm The phase difference between two particles separated by distance 10 cm will be 240 1 Zero 3 T 2 EN 2 4 Either 0 or

9 Stationary waves are formed on stretched string If the wavelength is A then the distance between two points having maximum displacement can be 2 4 4 All of these 1 3 2 3 5 2

5 A travelling wave pulse is given by 20 m then 4 x 4t 1 The pulse is travelling along negative x axis 2 The speed of pulse is 4 m s 3 The amplitude of pulse is 5 m 4 All of these y

2 A uniform string of length 20 m is suspended from a rigid support A short wave pulse is introduced at its lowest end It starts moving up the string The time taken to reach the support is Take g 10 ms 1 2n 2s 2 2s 3 2 2s 4 2s

A possible means for making an airplane invisible to radar is to coat the plane with an antireflective polymer If radar waves have a wavelength of 3 00 cm and the index of refraction of the polymer is n 1 50 how thick would you make the coating

4 X 1 English A Stretched wire of length 110 cm is divided into three segments whose frequencies are in ratio 1 2 3 Their length must be Question Type Single Correct Type 2 3 120 cm 30 cm 60 cm 60 cm 30 cm 20 cm 60 cm 20 cm 30 cm Review 4 30 cm 60 cm 20 cm

The equation of a simple harmonic wave is given by y 3 sin 50 t x 2 where x and y are in metres and t is in seconds The ratio of maximum particle velocity to the wave velocity is Question Type Single Correct Type 1 2 3 2 WIN 3 3 2

other end of the string is connected to rigid support passes over a smooth pulley as shown in the figure The horizontal part of the string has length 100 m and oscillates due to formation of standing wave with same frequency as that of bob Mass per unit length of the string is the following questions Q 17 M 100L 100 m Take L 10 m g 10 m s and answer M

If p and q are distance of object and real image from the principal focus of a concave mirror then the apeticion between p q and fis pq f 3 pq f 2 pq f 4 f

5 BEATS Beat phenomenon is physically meaningful only if 1 w w w 00 2 w w w 0 3 17 2 4 0 0 2

113 114 1 0 2 0 3 0 4 10 A closed pipe has certain frequency Now its length is halved Considering the end correction its frequency will now become 1 double 2 more than double 4 four times frequency of a closed 3 less than double The fundamental is n Ita

25 Source and observer both start moving simultaneously from origin one along x axis and the other along y axis with speed of source 2 speed of observer The graph between the apparent frequency observed by observer f and time t would be a for c fo b d fo fo

A tuning fork of frequency 340 Hz is held vibrating at the open end of an empty measuring cylinder of length 100 cm Water is then poured in it slowly What is the minimum height of water in cylinder for which resonance will be obtained Velocity of sound in air 340 m s Neglect end correction A B C D 25 cm 75 cm 80 cm 50 cm

A particle is oscillating according to the equa tion X 7 cos 0 5 nt where t is in second The point moves from the position of equilib rium to maximum displacement in time A 4 0 second B 2 second D 0 5 second C 1 0 second

35 The fundamental frequency of a sonometer wire of length lis fo A bridge is now introduced at a distance of Al from the centre of the wire Al 1 The number of beats heard if both sides of the bridges are set into vibration in their fundamental modes are 8f04 1 2f04 a c b d foAl 1 4f0Al

simple harmonic oscillation is 13 of its amplitude Ans E E 8 9 E E 1 9 A particle executes simple harmonic motion with time period 15 seconds and having amplitude 2 2m Find its maximum velocity and acceleration Ans 0 92m sec 0 38m sec

tions 04 Variation in Loud Variation in Loudness Level in a medium In a homogeneous medium loudness level of sound is different at different locations and it varies between 30 dB and 43 98 dB If in medium only two sonic waves of same frequencies but of different amplitudes exist from a single source Calculate the intensities of these two waves de live whe

twice the diameter twice the tension and twice the density of string B The overtone of A that will be in unison with fundamental frequency of Bis 1 4th 23rd 3 1st 4 2nd 39 A uniform rope having mass hangs vertically from rigid support A transverse wave pulse is produced at the lower end The frequency of wave pulse varies with x from the lower ends as ww 2 Ja Le T R 2 1 JB 4 Ja 1 40 The first overtone of an open organ pipe has frequency f The second overtone of a closed organ pipe of the same length will have frequency neglect end corrections 5f 2 5f 4 v Jgn J v gn 3f 2 3f 4 41 The equation of stationary wave is y 10 cos TX sin 100 where x is in cm and 10 tis in s The wave is formed on a string of length 40 cm An antinode will be located at from the following options F 2 4 He 2 x 25 cm 3 x 20 cm 4 x 12 5 cm 42 A motor cycle starts from rest and accelerates along straight path with an acceleration of 4 m s away from a stationary electric siren How far the motor cycle must have travelled when the rider hears the frequency of siren at 90 of its value when motor cycle was at rest speed of sound 330 m s 1 136 m 2 156 m 3 76 m 4 196 m To 43 The equation of a travelling wave on 2 string moving in positive x direction is given by y Asin ot kx It is reflected from a rigid boundary at x 0 The equation of rellected wave is y CE 1 Asin of kx 2 Asin cot kx 3 Asin of kx 4 Acos ot kx 44 The velocity time v t graph of a particle executing S H M is shown below The acceleration of the 5 3 particle at t s will be V 5 cm s 3 cm s 1 2 3 5 3 2 5K 3 2 5 0 cm s 2 av v r 4 F v cm s cm s 3 76 6 J 4 Zero 45 Which of the following quantity is always negative in SHM2 Symbols have usual meanings Fr cos 90 O 9 Costo 20 t s vtu 330 330 1 5 tamax 1

Diffraction pattern is obtained using red light What will happen if it is replaced by violet light Bands will get spaced apart Bands will remain fixed at same place Intensity pattern on screen will become 100 times Bands will come closer on screen

You observe a star in another galaxy You compare its brightness with another star with the same pulsation period in your own galaxy with a known distance of d 1x10 4 light year the star in the other galaxy is 10 9 times fainter How far away is the other galaxy Express in light years

18 A sonometer wire is emitting a note of frequency n when stretched by 1 point a weight If the weight is completely immersed in water then the frequency of the wire a will be zero b will not change c will decrease d will increase

17 A sonometer wire of length 1 metre Vibrates in 4 loops The distance between two consecutive nodes is O a 10 cm Ob 25 cm O c 50 cm O d 60 cm

30 Equations of two progressive waves at a certain point in a medium are given by y a sin wt 1 and y2 asin wt 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 01 02 is T a c 3R6 b d 2 3 TC

0 The string of a sonometer is divided into two parts using wedge Total length of string is 1m and two parts differ by 2mm When sounded together they produce 2 beats sec The freqencies of two parts are 1 501Hz 503Hz 2 501Hz 499Hz 3 499Hz 497Hz 4 497Hz 495Hz 3

29 A conveyor belt moves to the right with speed v 300 m min A pieman puts pies on the belt at a rate of 20 per minute while walking with speed 30 m min towards a receiver at the other end The frequency with which they are received by the stationary receiver is a hovud a 26 67 min c 22 22 min b 30 min d 24 min

12 In resonance tube experiment we use Oa transverse progressive waves Ob longitudinal progressive waves O c longitudinal stationary waves Od transverse stationary waves

9 In a resonance tube experiment tube has radius of 3 cm then its end correction is a 0 9 cm Ob 0 5 cm O c 0 9 m d 1 8 cm 1 point

23 A string is under tension so that its length is increased by times its original length The ratio of 1 n fundamental frequency of longitudinal vibrations and transverse vibrations will be a 1 n c n 1 b n 1 d n 1

11 An air column closed at one end and open at the other resonates with a tuning fork when the smallest X length of the column is 50 cm The next larger length of the column resonating with the same tuning fork is 2016 1 a 66 7 cm c 150 cm b 100 cm d 200 cm

The spectral line for a given element in light received from distant star is shifted towards longer wavelength side by 0 025 What is speed of star in line of sight O 2 5 x 104 ms 1 O 6 2 x 104 m s 1 O 7 5 x 104 m s 1 O 3 6 105 m s 1

19 A string of length 0 4 m and mass 102 kg is tightly clamped at its ends The tension in the string is 1 6N Identical wave pulses are produced at one end at equal intervals of time At The value of At which allows constructive interference between successive pulses is a 0 05 s b 0 10 s c 0 20 s d 0 40 s

A wave in a string has an amplitude 2 cm The wave travels in the ve direction of axis with a speed of 128 m s and it is noted that complete waves fit in 4 m length of the string Th equation describing the wave is a y 0 02 m sin 15 7 x 2010 b y 0 02 m sin 15 7 x 2010r c y 0 02 m sin 7 85x 1005t 10 IN