Waves Questions and Answers

For the travelling harmonic wave y x t 2 os2 10t 0 008x 0 35 where x and y are in cm and t is in s The phase difference between oscillatory motion of two points separated by a distance of 0 5 m is 1 0 2 rad 3 0 67 rad 2 0 4 rad 4 0 87 rad

A heavy string is tied at one end to a movable support and to a light thread at the other end as shown in figure 15 E12 The thread goes over a fixed pulley and supports a weight to produce a tension The lowest frequency with which the heavy string resonates is 120 Hz If the movable support is pushed to the right by 10 cm so that the joint is placed on the pulley what will be the minimum frequency at which the heavy string can resonate O 10 cm

The x y co ordinates of the corners of a square plate are U edges of the plate are clamped and transverse standing waves are set up in it If u x y denotes the displacement of the plate at the point x y at some instant of time the possible expression s for u is are a positive constant 1998 A a cos xx 2L cos y 2L C a sin x L sin 2y L B a sin x L sin Ty L D a cos 2 x L sin y L

Two point sound sources S and S are both of the same power and send out sound waves in the same phase The wavelength of both the waves is 48 5 m The intensity due to S alone at D is 25 W m The resultant intensity at D is I Find I in W m S 5 km 3 km S 4 km D

71 In Fig 2 99 if a parallel beam of while light is incident on the plane of the slits then the distance of the nearest white spot on the screen from O is assume d D Ad d 2d 3 Fig 2 99 b d 2

2 A fish in an aquarium approaches the left wall at a rate of 3 ms 1 and observes a fly approaching it at 8 ms 1 If refractive index of water is 4 3 what is the actual velocity of fly 1 4 25 m s 1 3 3 75 m s 1 Aquarium 2 3 2 m s 1 4 1 75 m s 1

17 When a wave travels in a medium displacement of a particle is given by y a sin 2 bt cx where a band care constants The maximum particle velocity will be twice the wave velocity if MHT CET 2014 1 d c a b ac 1 b b c c

For an amplitude modulated wave the maximum amplitude is found to be 10V while the minimum amplitude is found to be 2V Determine the modulation index What would be the value of if the minimum amplitude is zero volt

Two identical waves each of frequency 10Hz are traveling in opposite directions in a medium with a speed of 20 cm s The distance between adjacent nodes is

A sonometer has two strings stretched side by side parallel to each other The two strings are made of the same metal and have uniform cross sections of radii r and r2 respectively with r r 2 3 The two strings are each of length 1m and are loaded by identical weights The first string is made to oscillate with six loops in its length How many loops will be seen on the second string when it resonates with the first string Question Type Single Correct Type 12 2 3

5 A mica strip and a polysterene strip are fitted on the two slits of a double slit apparatus The thickness of the strips is 0 50 mm and the separation between the slits is 0 12 cm The refractive index of mica and polysterene are 1 58 and 1 55 respectively for the light of wavelength 590 nm which is used in the experiment The interference is observed on a screen a distance one meter away a What would be the fringe width b At what distance from the centre will the first maximum be Xocated

Two coherent radio frequency point sources separated by 2 0 m are radiating in phase with A 1 0m A detector move in a circular path of large radius around the two sources in a plane containing them The number of maximum detected by the detector is

1 The equation of a plane progressive wave is y 0 02 sin 87 1 2 When it is reflected at a rarer 20 medium its amplitude becomes 75 of its previous value The equation of the reflected wave is a y 0 02 sin 87t 20 X c y 0 015 sin 8 1 20 b y 0 02 sin 8m 1 20 X d y 0 015 sin 8 1 20

Q 19 A white light ray is incident on a glass prism and it creates three refracted rays A B C and one reflected ray D Select the correct alternative s 1 D are total internally reflected rays D white light A Best possible colour for A is red B is green C is yellow and D is blue B Best possible colour for A is red B is yellow C is green and D is blue C Best possible colour for A is blue B is green C is yellow and D is red D Best possible colour for A is blue B is yellow C is green and D is red

5 Four simple harmonic vibrations 05 601 1 2 V 8 cos oot V2 4 cos V3 2 cos t n V4 cos cos tot 377 are superposed on 2 each other The resulting amplitude and phase are respectively a 45 and tan 1 2 c 75 and tan 1 2 b 45 and tan 1 3 d 75 and tan 1 3

30 A 50 cm long wire of mass 20 g supports a mass of 1 6 kg as shown in figure Find the fundamental frequency of the position of the string between the wall and the pulley a 25 Hz c 75 Hz 40 cm 15 kg 10 cm b 50 Hz d 100 Hz

5 The speed of transverse wave giving on a wire having a length 50 cm and mass 5 0 g is 80 m s The area of cross section of the wire is 1 0 mm and its Young s modulus is 16 x 10 1 N m Find the extension of the wire over its natural length a 0 04 mm c 0 06 mm b 0 02 mm d 1mm

The length of the wire between two ends of a sonometer is 100 cm What should be the positions of two bridges below the wire so that the three segments of the wire have their fundamental frequencies in the ratio 1 3 5 NEET Karnataka 2013 1500 300 23 23 a c 1500 23 300 23 cm cm 500 23 1500 23 cm b d 1500 23 cm cm cm 2000 23 cm

A point object is placed at a distance of 20 cm from 4 20cm a thin plano convex lens of focal length 15 cm If the B plane surface is silvered the image will from at 1 60 cm from left of AB 2 30 cm from left of AB 3 12 cm from left of AB 0 60 cm from right of AB

149 An engine moving towards a wall with a velocity 50 m emits a note of 1 2 kHz The speed of sound in air is 3 m s The frequency of the note after reflection from the wi as heard by the driver of the engine is 1 2 4 kHz 2 0 24 kHz 3 1 6 kHz 4 12 kHz

The first resonance length of a resonance tube is 40 cm and the second resonance length is 122 cm the third resonance length of the tube will be Question Type Single Correct Type 1 2 3 4 200 cm 202 cm 203 cm 204 cm

Go to Ove Pleas Sec QNO 11 Correct Answer 4 Status unattempted Full Paper 2 The equation of a simple harmonic wave is given by y 3 sin 50t x where x and y are in metres and t is in seconds The ratio of maximum particle velocity to the wave velocity is 23 33 Physics 2 Add to Bookmark List ENIM MIN Q No Complete Question Content The equation of a simple f Question Status Marks Tim

In a sonometer wire When the tension is maintained by suspending a 20 kg mass from the free end of the wire the fundamental frequency of vibration is 300 Hz If the tension is provided by two masses of 5 kg and 15 kg suspended form a pulley massless and friction less as shown in the figure the fundamental frequency will 5kg 15kg

4 In a Young s double slit experiment the fringes are displaced by a distance x when a glass plate of refractive index 1 5 is introduced in the path of one of the beams When this plate is replaced by another plate of same thickness the shift of fringes is 3 2 x The refractive index of second plate is a 1 75 c 1 25 b 1 40 d 1 67

1 In Young s double slit experiment how many maximas can be obtained on a screen including the central maximum on both sides of the central fringe if 2000 and d 7000 a 12 c 18 b 7 d 4

A wave pulse on a string has the dimensions shown in figure The wave speed is v 1 cm a If point O is a fixed end draw the resultant wave on the string at 1 3s and 1 4s b Repeat part a for the case in which O is a free end 1 cm 1 cm 1 cm v 1 cm s 2 cm

In YDSE with two identical slits when upper slit is covered with a transparent sheet of mica second order minima is observed above the centre of the screen and second order maxima below it Which of the following can not be possible value of phase difference caused by the mica sheet e 2 7 3 10 11m

3 A block of mass m 2 kg is attached to a spring with spring constant k 20 N m The block was pulled a distance A 5 cm from equilibrium along the positive x axis Now solve the following problems a 1 marks Find the total energy of the system b 6 marks Find the velocity acceleration and the angular frequency of the block when t 2s Also indicate their directions c 3 marks Show that at any time t the total energy of the system is conserved

Question No 69 Single Correct A A A wave is represented by y Asin kx wt o The amplitude and wavelength of wave is given by A 2A B C D A 2T k 2n k A 2 2 k A T 2 k

A wave is represented by y Asin kx wt p The amplitude and wavelength of wave is given by 2A A 2T k 2T k Single Correct A A A 2 2 k

An earthquake generates both transverse S and longitudinal P sound waves in the earth The speed of 5 waves is about 6 km s and that of P waves is about 9 km s A seismograph records P and S waves from an earthquake The first P wave arrives 5 minute before the first 5 wave The epicentre of earthquake is located at a distance about D 54 km 540 km 5400 km Marks 4 00 1 00 72 km

A In a stationary wave represented by y 2a sin kx cos wt the intensity at a certain point is maximum when B cos kx is maximum cos kx is minimum sin ot is maximum A sin ot is minimum A

Q79 In a diffraction pattern due to a single slit of widt a the first minimum is observed at an angle 30 whe light of wavelength 5000 is incident on the slit Th first secondary maximum is observed at an angle of a sin 1 b sin 1 c sin 1 d sin 1

A block M hangs vertically at the bottom end of a uniform rope of constant mass per unit length The top end of the rope is attached to a fixed rigid support at 0 A transverse wave pulse Pulse 1 of wavelength X is produced at point O on the rope The pulse takes time TOA to reach point A If the wave pulse of wavelength Ao is produced at point A Pulse 2 without disturbing the position of M it takes time T O to reach point O Which of the following options is are correct Pulse 1 I Pulse 2 AM The time TAO TOA The wavelength of Pulse 1 becomes longer when it reaches point A The velocity of any pulse along the rope is independent of its frequency and wavelength The velocities of the two pulses Pulse 1 and Pulse 2 are the same at the midpoint of rope Solution Answer A C D At any point v F since velocity depends on tension at a point and mass per unit length so time from 0 to A and A to O will be same V TOA TAO Also frequency remain constant at all point To must be same and vis keep it same maximum at O T maximum so must be

A glass prism 1 5 is dipped in water 4 3 as shown in figure A light ray is incident normally on the surface AB It reaches the surface BC after totally reflected if Question Type Single Correct Type 1 2 3 sine 8 9 2 3 sine 8 9 B sine 2 3

y a cos kx wt superposes on another wave giving a stationary wave having node at x 0 What is the equation of the other wave Question Type Single Correct Type 1 2 3 4 a cos kx wt a cos kx wt a cos kx wt a sin kx wt

4 At what temperature will the speed of sound in air becomes 3 times of its value at 0 C NCERT XI Pg 391 1 1184 C 3 2184 C 2 1148 C 4 2148 C of frequency 8 Equation of given by y from a d becomes

ar A fish in an aquarium approaches the left wall at a rate of 3 ms observes a fly approaching it at 8 ms 1 If refractive index of water is 4 3 what is the actual velocity of fly Aquarium O 4 25 m s 1 0 3 2 m s 1 0 3 75 m s 1 1

A person wears glasses of power 2 5D What is the far point of the person without the glasses Question Type Single Correct Type 1 2 3 4 40 cm 20 cm 15 3 cm 15 3 cm

If the length of the string is L then its first end can be de as x L Ju This relation gives the expression for th V nv 2L n T 2L modes We thus obtain the normal modes of oscillation of the sys

There is a cylindrical vessel of cross sectional area 20 cm and length 1m is initially filled with water to a certain height as shown There is a very small pinhole of cross sectional area 0 01 cm at the bottom of the cylinder which is initially plugged with a pin cork The air column in the cylinder is resonating in fundamental mode with a tuning fork of frequency 340 Hz Suddenly the pin cork is pulled out and water starts flowing out of the cylinder Find the time interval after which resonance occurs again Given velocity of sound in air 340 m s

0 Figure shows a graph of particle displacement function of x at t 0 for a longitudinal wave travelling in positive x direction in a gas A B C D denote position of particles in space A B C D Column I point A point B point C point D den B D AS A P Q R S T X Column II Particle velocity is in direction of wave propagation Maximum magnitude of strain Excess pressure is zero Maximum density Maximum magnitude of excess pressure

Sinusoidal waves travel on five identical strings Use the mathematical forms of the waves given below n the expressions given below x is in m and y is in millimeters and t is in seconds a y 2mm sin 2x 4t b y 3mm sin 4x 10t c y 2 5mm sin 6x 12t d y 1mm sin 8x 16t e y 4mm sin 10x 20t Four of the strings have the same tension but the fifth has a different tension Identify it

A plane progressive wave of frequency 50 Hz travelling along positive x axis is represented as y 5 x 10 5 m sin 100nt at x 0 wave speed is 300 m s Maximum difference in displacement at x 0 and x 3m is a 5 10 5 m b 2 5 10 4 d 104 m c 5 104 m

A body execute SHM according to equation x 10 cos 2 t 4 At t 3 2 s what is speed of the particle NCERT Pg 339 1 10 ms 1 2 20 ms 1 3 22 ms 1 4 44 ms 1 5

4 Young s experiment is performed with light of wavelength 6000 wherein 16 fringes occupy a certain region on the screen If 24 fringes occupy the same region with another light of wavelength then is a 6000 b 4500 c 5000 d 4000

For the arrangement shown in the fig the tension in the string is 1 Question Type Single Correct Type 2 3 4 6 N 6 4 N 0 4 N 30 Zero m 1kg H 0 8

44 Two sonometer wires of the same material have equal tension If the ratio of their lengths is 2 1 and the ratio of their cross sectional radii is 1 4 then the ratio of their fundamental frequencies is A 2 1 B 1 2 C 1 1 D 2 1 45 In the given circuit the equivalent resistance between the points P and Q is A 40 P B 20 192 192 M 292 WN 352 WN 392 Q MY 100

Travelling sinusoidal transverse wave is present on a string which is spread along x axis Acceleration of particle at x 0 and particle at x 2 cm are shown Both the particles are separated by distance less than half wavelength x 0 x 2 AX Gast IN A At time t 0 particle at x 8 cm is moving towards its mean position B At time t 0 particle at x 8 cm is moving in upwards direction C Wave is travelling in x direction D At time t 0 magnitude of displacement of particle at x 8 cm is half the amplitude

Ari is sitting near a loud speaker that emits sound of frequency 606 9 Hz Max pushes another loud speaker towards Ari at 3 m s emitting a sound of frequency 585 7 Hz If the speed of the sound waves in air is 340 m s then what is the beat frequency heard by Ari