Magnetism and Matter Questions and Answers

Please explain why a b and d are correct options Please give reason for each option 4 A charged particle moves in a gravity free space without change in velocity Which of the following is are possible b E 0 B 0 d E 0 B 0 Jang a single under the action Asked by 1008645 aesl id Standard XI Stream NEET Jul 13 2021 at 2 06 PM a E 0 B 0 c E 0 B 0 4

A horizontal straight wire 20 m long extending from east to west is falling with a speed of 5 0 m s at right angles to the horizontal component of the earth s magnetic field 0 30 x 104 Wb m The instantaneous value of the e m f induced in the wire will be 2012 B 6 0 mV D 4 5 mV A 1 5 mV C 3 mV

In the magnetic meridian of a certain place the horizontal component of earth s magnetic field is 0 48 G and the dip angle is 53 Magnetic field of the earth at this location is NCERT Pg 188 1 0 3 G 2 0 8 G 3 0 64 G 4 0 96 G

The self inductance L of a solenoid of length I and area of cross section A with fixed number of turns per unit length increases as NCERT Pg 223 1 and A increases 2 decreases and A increases 3 Both and A decreases 4 Lincreases and A decreases

Q 2 A vessel is filled with a gas at a pressure of 76 cm of mercury at a certain temperature The mass of the gas is increased by 50 by vidio introducing more gas in the vessel at the same temperature The resultant pressure in cm of Hg is 1 76 3 114 C TL 2 152 to 4 1117 al 2

A coaxial inner conductor is solid and of radius R The outer conductor is hollow and of inner radius R2 and outer radius R3 The space between the conductors is filled with air The two conductors carry equal currents but in opposite directions The variation of magnetic field with distance from common axis plotted is best the as R R R 1 2 3 18 B B R R R r R R R R R R B h R3 SB de

figure i iii Tt a iv 1 diagram for an ideal gas shown in Out of the following diagrams which figure represents the T p diagram T 2 1 2 P 1 p p b ii constant V 2 ii V Th iv Tt 21 1 c iii foggos p 2 P d i

5 42 The rails of a railway track are 1 5m apart and assumed to be insulated from one another Calculate the EMF that will exist between the rails if a train is passing at 100km hr Assume the horizontal component of earth s magnetic field is 0 36 104T and tan 0 1 036 where 0 is the angle of dip X Ans 1 554 x 10 V1

4 All of the above The magnetic needle shown in the figure has magnetic moment 6 7 x 10 2 A m and moment of inertia 7 5 x 10 6 kg m It performs 10 complete oscillations in 6 70 s The magnitude of magnetic field is

Q15 Square coll A has 2N turns and sides of length L and square coll B has N turns and sides of length 2L When a current of 2 amps is sent through coil A and a current of 1 amp is sent through coll B which coll has the greater magnetic moment O A Both have the same magnetic moment O B More information is needed O C coll A O D coll B

The hysteresis loss per cycle per unit volume for soft iron is 10 Joule The density of iron is 7 5 gm cm and its specific heat is 100 cal kg C If a specimen of soft iron is subjected to an alternating magnetic field of frequency 50 Hz then rise per minute in its temperature will be

A magnetic needle lying parallel to a magn field requires W unit of work to turn it through The torque needed to maintain the needle in position will be 1 W 2 2W 3 3W 4 W

i Find the self inductance of a unit length of a cable consisting of two thin walled coaxial metallic cylinders if the radius of the outside cylinder is n n 1 times that of the en by the inside one The permeability of the medium between the cylinders is assumed to be equal to unity Ho In n 2

A flux of 900 Wb is produced in the iron core of a solenoid When core is removed a flux in air of 0 5 Wb is produced in same solenoid by same current What is relative permeability of iron O 1200 O 900 O 1600 O 1800

Can we directly do sin 135 here By diagram normal and f eld are at 135 A rectangular coil of length 0 12 m and width 0 1 m having 50 turns of wire is suspended vertically in a uniform magnetic field of strength 0 2 Wb m The coil carries a current of 2 A If the plane of the coil is inclined at an angle of 30 with the direction of the field the torque required to keep the coil in stable equilibrium will be 1 0 15 Nm 2 0 20 Nm 3 0 24 Nm 012 Nm

The period of oscillation of a magnet of a vibration magnetometer is 2 45 s at one place and 4 9 s at the other The ratio of the horizontal component of earth magnetic field at the two places is 1 1 4 3 2 1 2 1 2 4

The length of a magnet is very large as compared to its width and breadth The time period of its oscillation in a vibration magnetometer is 2 s The magnetic is out perpendicular to its length into three equal parts and three parts are then placed on each other with their like poles together The time period of this combination will be 1 2 s 2 2 3 S

A thin magnetic needle is oscillating freely suspended in a magnetic field with time period 4 sec If it is divided into two equal parts and one part is again suspended in the same field to oscillate freely then what will be its time period 1 2 sec 2 8 sec 3 1 sec 4 4 sec

A weightless rod with length I is rigidly attached to a weight less pulley with a radius r The end of the rod carries a mass m A string to whose free end a mass M is fastened is passed over the pulley Pulley is free to rotate about its own axis horizontal For a 30 the system will be in equilibrium If the system is disturbed slightly over its equilibrium position it oscillates with angular frequency then N where N 1 given that 34 1 316 2mgl Mr ml M Aus 66

In the figure shown S and S are two coherent sources emitting light of wavelength A and having zero initial phase difference S and S oscillate simple harmonically with amplitude a each and angular frequency w each on line PQ which is perpendicular to x axis The initial position and initial direction of motion of S and S are shown S and S are at their mean position at t 0 Then rate of change of fringe width at time t is XDw T 3w a x then x 2y equals Assume that a and a D and x y are integers B c urfuch cellar m 3 fa XDw 2 a x y 2a 2a z 3ad su atma ge urfag Kufa au uefug fe teft 1 x y quic1 P S u 2 aface Gaung Haar Gad T 3w S J t 0 g f 43 uz 31 2 uRada 6z ar Hai fch a D Correct Answer 10

1 A cylindrical piston of mass M slides smoothly inside a h long cylinder closed at one end enclosing a certain mass of gas The cylinder is kept with its axis horizontal If the piston is disturbed from its equilibrium position it oscillates simple harmonically The period of oscillation will be 1 T 2n 3 T 2T Mh PA M DAL Gas 2 T 2n P MA Ph 4 T 2 MPhA A M

A magnetised wire of magnetic moment 2m A m is bent in the form of a quarter circle The new moment of the wire is O 2 Am O2 2 Am O 4 2 Am 2 Am

The time period of oscillation of a bar magnet in a vibration magnetometer is 4 s The magnet is cut along its length in four equal parts and these pa are tied one over the other with like poles together The time period of this new combination will be O 2 s O 4 2 s O 2 2 s O 4s

In a vibration magnetometer the time period of oscillations of two bar magnets together is increased to the ratio 1 when one of the bar magnets is reversed The ratio of the magnetic moment of the bar magnets is 2 1 O 3 1 04 1 061

The true value of dip angle shown by a dip circle is 45 If the plane of the dip circle is rotated by 60 the new dip angle will becomes Otan 2 Otan 2 O tan O tan 2 3

A conducting rod of length and mass mis released from rest at r 0 in magnetic field on parallel rails to move vertically downward due to gravity as shown in figur Mark correct statement by assuming there is no dielectric breakdown m I 0 Velocity of rod at time r is equal to mgt m B FC Acceleration of rod keeps decreasing but velocity of rod keeps increasing Acceleration of rod keeps decreasing while velocity of rod increases till it attains terminal velocity Acceleration of rod is constant and velocity of rod keeps increasing

Q 10 A plane 3 frequency of 2 0 x 10 0 Hz and its energy density is 1 02 108 J m in vacuum The amplitude of the magnetic field of the wave 1 Nm C and speed of is close to 9 10 4 TE light 3 108 m s 1 160 nT 2 180 nT

The region between y 0 and y d contains a magnetic field B B2 A particle of mass m and charge q enters the region with a velcoity v vi If d acceleration of the charged particle at the point of its emergence at the other side is JEE Main 2019 January 3533 1 qvB m 2 mv 2qB qvB 3 m 2 1 1 the

a uniform magnetic field B B cos cor perpendicular to the plane of the spiral see figure The total electromotive force induced in the spiral between points A and C is approximately Assume N 1 A 2n Bowh N sin cor 3 Bowh N sin cot AC B D Booh N sin cot 3 Bowh N sin cor

Question No 8 A bar magnet has a magnetic moment equal to 5 10 5 Wb m It is suspended in a magnetic field which has a magnetic inducting B equal to 8 10 4 Tesla The magnet vibrates with a period of vibration equal to 15s The moment of inertia of the magnet is Mo 4 x 10 7 Wb A m Options 22 5 kg m 11 25 kg m 2

A conducting rod of length and mass m is released from rest at t 0 in magnetic field on parallel rails to move vertically downward due to gravity as shown in figure Mark correct statement by assuming there is no dielectric breakdown m 177 C X xxx X X XXXXXX X X X XXX X X X X X X Velocity of rod at time t is equal to mgt m B 1 C Acceleration of rod keeps decreasing but velocity of rod keeps increasing Acceleration of rod keeps decreasing while velocity of rod increases till it attains terminal velocity Acceleration of rod is constant and velocity of rod keeps increasing

31 The magnetic susceptibility of a magnetic material at 227 C is 0 00002 Then magnetic susceptibility of material at 727 C will be 1 0 00002 2 0 00004 3 0 00001 4 0 00008 32 All straight wires are very long Both AB and CD Medi

Test 10 Code A 26 There are four identical metal plates each of area A The plates are placed at equal distance d A successively as shown in figure If 2 F and source of emf 10 V is connected between x and y then charge on plate x will be A 1 0 4 V 3 0 2 V B 1 30 C 2 10 C 3 20 C 4 20 C 27 The current flowing in the given circuit is 0 2 A The potential difference between the points A and B will be 392 1 3 202 L iB 4n 6 V 3 10 4 V 2 2 V 4 1 V 28 Current is carried in a wire of length L If the wire is turned into a circular coil The maximum magnitude of torque acting on it when placed in a given uniform magnetic field B will be LiB 2 4 10 V LIB 2 LPB 4x B Medica 29 The relation between voltage sensitivity and the current sensitivity of a moving coil galvanometer is Given G is the resistance of the galvanometer 1 Go 1 3 6 0 G 30 If a coil of 50 turns area 5 0 cm is suddenly removed from magnetic field It is observed that charge of 5 x 10 C flows into the coil If the resistance of the coil is 100 2 the magnetic flux density in Wb m is 31 1 1 3 2 A transformer is used to light 150 W 30 V lamp from a 240 V mains The current in the main cable is 0 8 ampere The efficiency of the transformer is nearly 1 78 3 88 32 In the circuit shown there is a box containing a resistance R and inductance L and a capacitor of capacitance C connected in series to an alternating source of angular frequency 4 rad s Box has power factor and the circuit has overall power factor 1 The impedance of the box 3 is 34 1 3 3 4 2C 4 2C 33 Let P and E denotes the linear momentum and energy of photon If the wavelength is decreased 1 Both P and E decrease 2 Both P and E increase 3 P increase and E decrease 4 P decrease and E increase The number of photons emitted per second by monochromatic light of Online Mock Test Series for NEET 2020 2 3 4 4 3 60 W source of wavelength 5000 A is 1 1 5 x 1020 3 3 5 1020 35 The ratio of magnetic dipole moment to angular momentum in a hydrogen like atom is 2 48 4 92 3m 2 1 5 x 10 18 4 3 5 10 18 2 4 4m 2m

A dipole of dipole moment p is placed in a non uniform electric field along x axis Electric field is increasing at the rate of 1 V m then the force on dipole is 1 O 3 p 2 2 2p 4 p MODULE 04 1 ELECTROSTATICS02 EXERCISE P65

In the pulley system shown in figure the movable pulleys A B C are of mass 1 kg each D and E are fixed pulleys The strings are vertical and inextensible Find the tension in the string to the nearest integer value in SI unit DVE ptions

ample 21 A square loop of side I carries a current i It is placed as shown in figure Find the magne moment of the loop Magnetic moment M i A ABXBC AB cos 30 i sin 30 k BC 11 ution cos 30 sin 30 k 11 12 2 So magnetic moment 12 3x 2 M i 1 3k 2 y A i lios 30 130 B i C X

32 A square coil of edge length I having n turns carries a current I It is kept on a smooth horizontal plane A uniform magnetic field B exists in a direction paralle to an edge The total mass of coil is m What should be the minimum value of B for which the coil wil start toppling 1 3 mg nll 2mg nll 2 4 mg 2nll 4mg nll

Online Mock Test Series for NEET 2020 33 A compass needle which is allowed to move in a horizontal plane is taken to a geomagnetic pole It 1 will stay in North South direction only 2 will stay in East West direction only 3 will become rigid showing no movement 4 will stay in any position corios R cinusoidal pir Courco 35

A short bar magnet is placed with its axis 30 with an external magnetic field of 0 8 T experiences a torque of 0 016 N m How much work is required to turn it to 90 with magnetic field from this position 0 028 J 0 073 J 0 06 J 0 35 J

Consider a uniform square wire frame OABC carrying current I Each side of frame is of length a and the longitudinal mass density of frame is u The frame is free to rotate around upper side OA Find the magnitude of uniform magnetic field B in positive y direction in Tesla required to hold the frame tilted 45 away from vertical axis as shown in figure g 10 m s i I 2A u 0 5 kg m Z 45 B 45 O TB B C

The electrostatic charge density p r corresponding to the potential 9 1 ar or exp 2 p r 4 a qo r 2qa exp ar 1 exp ar is p 470 c go r qexp ar b g r q exp ar d gd r 2ga exp ar

The lengthofa magnetis large compared to its width and breadth The time period of its oscillation in a vibration magnetometer is 2 s The magnet is cut along its length into three equal parts and three parts are then placed on each other with their like pales together The time period of this combination will be A 2s B 2 3 s C 2 3 D 2 3s A L E E E 2004

moment u It is initially in equilibrium with its plane perpendicular to a magnetic field of 91 magnitude B If it is now rotated through an angle 8 towards the magnetic field the work done is 1 B0 3 uB 1 cose 2 B cos 0 4 Bsine H TITLE Registered Office A tional Services Limited

Ans 3 8 An iron rod of susceptibility 599 is subjected to a magnetising field of 1200 Am The permeability of the material of the rod is Ho 4 x 10 7 Tm A 1 2 4m x 107 Tm A 2 2 4m x 104 Tm A 3 8 0 x 10 5 Tm A 4 2 4m x 10 5 Tm A

30 The half value thickness of an absorber is defined as the thickness that will reduce exponentially the intensity of a beam of particles by a factor of 2 The half value thickness in um for lead assuming X ray beam of wavelength 20 pm u 50 cm 1 for X rays in lead at wavelength 20 pm ondig h is um

A short bar magnet is arranged with its north pole pointing geographical north It is found that the horizont component of earth s magnetic induction B is balanced by the magnetic induction of the magnet at a poi which is at a distance of 20 cm from its centre The magnetic moment of magnet is if B 4 10 Wbm 1 3 2 Am 2 1 6 Am 3 6 4 Am 2 4 0 8 Am

The graph shows the variation in magnetic flux o t with time through a coil Which of the statements given below is not correct dar B C p t T B 4 C A D There is a change in the direction as well as magnitude of the induced emf between B and D 162 The magnitude of the induced emf is maximum between B and C There is a change in the direction as well as magnitude of induced emf between A and C

A magnetized wire of magnetic moment M is bent into an arc of a circle that subtends an angle of 60 at the centre The equivalent magnetic moment is 1 M T 2 2M TT 3 3M TC 4 4M TU A llevim

Q10 a bimetallic strip is made of aluminium and steel AL asteet On heating the strip will a remain straight b get twisted c will bend with aluminium on concave side d will bend with steel on concave side

A sphere of mass 2m is in rolling state with velocity of centre vo on horizontal surface then net force exerted by upper hemisphere on lower hemisphere is vo Rg R is radius of sphere A 5 mg 8 mg Vo B D 9 mg 11 3 mg 5