Magnetic Field Questions and Answers

A 90 cm long solenoid has six layers of windings 450 turns each If the diameter of solenoid is 22c and current carried is 6 A then the magnitude of magnetic field inside the solenoid near its centres a 50m G b 60 G c 72n G d 80mG car in c dist the b

An proton travelling east to west enters a chamber having a uniform electrostatic field in south to north direction If proton is not deflecting from its straight line path then the direction of a uniform magnetic field Bis

a c 9 6 x 10 5 T 4 The correct plot of the magnitude of magnetic field B vs distance r from centre of the wire is if the radius of wire is R a b 8 34 x 10 d 10 2 x 10 ST c b d 0 60 The a F a b F n c b d b 61 Two and 5 unit le a 2 c 1

Four particles A B C and D of masses mA MB mc and mo respectively follow the paths as shown in the figure in uniform magnetic field X X X X X X X Dox X X Each particles are moving with same speed If A AB ac and ap are the specific charge of particles A B C and D respectively then All particles are moving in same plane 2r X O B O A A c B D O Charge on particle B and D is of same nature Charge on particle B and D are of different nature

Both currents attract d both currents repel 1 Two parallel wires 2 m apart carry currents of 2 A and 5 A respectively in same direction the force per unit length acting between these two wires is a 2 x 10 Nm c 1 x 10 6 Nm b 3 x 10 Nm d 4 x 10 6 Nm Co 2 69 11 of 11

d 4x 10 T vertical down If a long straight wire carries a current of 40 A then the magnitude of the field B at a point 15 cm away from the wire is a 5 34 x 10 5 T c 9 6 x 10 5 T b 8 34 x 10 5 T d 10 2 x 10 5T

a 2 4 x 10 T c 2 79 x 10 T b 3 5 x 10 T d 3 x 10 T The magnitude of the magnetic field at the centres of the tightly wound 150 turn coil of radius 12 cm carrying a current of 2 A is a 18 G b 19 7 G c 15 7 G d 17 7 G

2 Consider a circular coil of wire carrying constant current I forming a magnetic dipole The magnetic flux through an infinite plane that contains the circular coil and excluding the circular coil area is given by The magnetic flux through the area of the circular coil area is given by Which of the following option is correct 1 90 3 0 2 0

1 Five long wires A B C D and E each carrying current I are arranged to form edges of a pentagonal prism as shown in figure Each wire carries current out of the plane of paper the magnetic induction DO c at a point on the axis O is axis O is at a distance R from each wire is a equal to zero c more than zero EQ R b less than zero d infinite OB

b 6 5 c 10 6 d 12 6 36 An electron is moving in a cyclotron at a speed of 3 2 x 10 m s in a magnetic field of 5 x 10 T perpendicular to it What is the frequency of this electron 37 q 1 6 x 10 19 C m 9 1 x 10 1 kg a 1 4 x 105 Hz b 1 4 x 10 Hz c 1 4 x 105 Hz d 1 4 x 10 Hz arra pen in curi pap at a from a c

The figure shows two diamagnetic spheres located near the south pole of a bar magnet Then N C S 99 O 2 A The force on sphere 1 is directed towards the magnet B The force on sphere 2 is directed away from the magnet The magnetic dipole moment of sphere is directed towards the magnet D The magnetic dipole moment of sphere 2 is directed away from the magnet

d 2 A long straight wire in the horizontal plane carries a current of 75 A in north to south direction magnitude and direction of field B at a point 3 m east of the wire is a 4 x 10 b 5 x 10 c 5 x 10 d 4x 10 T vertical up T vertical down T vertical up T vertical down

MAGI 38 An element of 0 05 m is placed at the origin as shown in figure which carries a large current Im of 10 A The magnetic field at a distance of 1 m in perpendicular direction is a 4 5 10 T c 5 0 x 10 T Ax 0 05 m b 5 5 x 10 T d 7 5 x 10 T ing with velocity produces a 43 44

a 4 5 x 10 c 5 0 10 T d 7 5 x 10 T 9 If an electron is moving with velocity produces a magnetic field B then a the direction of field B will be same as the direction of velocity v b the direction of field B will be opposite to the direction of velocity v c the direction of field B will be perpendicular to the direction of velocity v d the direction of field B does not depend upon the direction of velocity v h uniform square frames as 40

d the the direction of velocity v Current flows through uniform square frames as shown in the figure In which case is the magnetic field at the centre of the frame not zero a c b d 41 Five long wires A B C D and Frant Lave TO 46 A ma flo a 47 A qu qu cen the a c

A small horseshoe magnet with a uniform magnetic field strength 0 55 T between its poles is placed on a weight scale A straight conducting wire is clamped in the space between its poles The length of wire between the poles s 4 0 cm When a current of 2 0 A is passed through the wire the value of the weight on the scale changes by what value Select one alternative O 0 021 O 0 044 N O 18 N O 0 15 N O 4 4 N

A charged particle of mass 2 Kg and 1 C starts at the origin with velocity 34 m s and travels a region of uniform magnetic field B 102 Wb m At t 4 sec do the following a Calculate the velocity and acceleration of the particle b Calculate the magnetic force on it c Determine its kinetic energy and its location d Find the particle s trajectory e Show that its kinetic energy remains constant

28 If an electron is moving in a magnetic field of 5 4 x 10 T on a circular path of radius 32 cm having a frequency of 2 5 MHz then its speed will be a 8 56 x 10 m s 1 b 5 024 x 100 m s c 8 56 x 10 m s d 5 024 x 10 ms 29 A proton and an a particle enter in a uniform 35 36

the magnitude of field is a 0 65 T b 1 53 T c 2 4 T d 32T A circular loop of radius R carrying a current Is placed in a uniform magnetic field B perpendicular to the loop The force on the loop is a 2 RIB c R IB b 2 RFB d zero c 4 14 A recta is hur of a ba figure added to ba

A proton and an a particle having kinetic energies Kp and K respectively enter into a magnetic field at right angles The ratio of the radii of trajectory of proton to that of a particle is 2 1 The ratio of Kp K is 1 1 8 2 8 1 3 1 4 thongo mathonga 4 4 1 mathongamathongo mathonge mathongo mathongo mathongo mathens mashanga mathongo mathongg mathongo mathonde mathongo mathongo mathong mathongo zam

A coil of 50 turns and 4cm radius carries 2A current then magnetic field at its centre is 3 14 mT 157 mT 15 7 mT 1 57 mT Marks 4 1

5 The magnetic force F on a current carrying conductor of length I in an external magnetic f B is given by a xB b 6 po you plan your next step All the Best IxB I c I B d Fix 2 13 A cir in a plane cross of co

15 AB is an infinitely long wire placed in the plane of rectangular coil of dimensions as shown in N the figure Calculate the mutual inductance of wire AB and coil PQRS B P Q In 2n b HOC 2 In 6 9 b A a S b c R Habc 2n b a d None of these a e a E 18

Magnetic Effects of Electric Current 14 11 A An insulated conducting rod in shape of a five point star like planar structure carries a current I In the regions to the left and to the right of a line A A2 uniform magnetic fields each of induction B exist perpendicularly into and out of the plane of the star as shown in the figure If length of a side of a unit cell of the grid shown is 1 find force of interaction between the current and the magnetic field B A B

A steady current I flows down a long cylindrical wire of radius a The current is distributed in such a way that J is proportional to s where s is the distance from the wire s axis Find the magnetic field inside and outside the wire

Knowing that the symbols represent indefinite long straight conductors carrying currents i1 2 4A and i2 7 B and A perpendicular to the plane of the paper and in the direction of the figure Determine the modulus of the magnetic field measured in microtesla resulting from the point P 7 7 4 3 cm Micro 10 5 Y ym x m X

In a region of space a radial magnetic field is established flux density B of which varies with distance r from the origin of a coordinate system according to the law B 3 r2 Here is a positive constant A small conducting ring of radius a and resistance R is placed parallel to the y z plane with its centre at point x 0 0 Find the force that must be applied on the ring to move it with a constant velocity vi Ans 42a4 B v R x a 3

B 7 A conducting wire of length 1 and cross section area A fixed grounded metallic supports is vibrating in its fundamental mode with a frequency vand amplitude a in presence of a uniform magnetic field of induction B pointing normal to the plane of vibration of the string Find an expression for electromotive force induced in the wire as a function of time t assuming the wire straight at t 0 481 Bd Cos 2x2

d 10 a 20 b 2 5 c 5 38 Four wires of the same diameter are connected in turn between two points maintained at a constant potential difference Their resistivities and lengths are p and L wire 1 1 2 p and 1 2 L wire 2 0 9 p and 0 9 L wire 3 and p and 1 5 L wire 4 Rank the wires according to the rates at which energy is dissipated as heat greatest first a 4 3 1 2 b 4 2 1 3 c 1 2 3 4 d 3 1 2 4

9 A full wave rectifier circuit along with the input and output are shown in the figure The contribution from the diode D is are 1 C 3 B D V Input V Input 00000 Output eedee D D KH ABCD 2 A C 4 A B C D Output

28 A negative charge is coming towards the observer The direction of the magnetic field produced by it will be as seen by observer 1 Clockwise 2 Anti clockwise 3 In the direction of motion of charge 4 In the direction opposite to the motion of charge

A circular coil of 200 turns and cross sectional area 24 cm carries a current of 5 A It is placed in a uniform magnetic field of strength 0 9 T with the plane of the coil making an angle of 300 with the direction of the magnetic field The torque acting on the coil is A 1 87 N B 1 08 N C 2 16 N D 3 74 N

ring of radius 20 cm has a total resistance of 0 040 A uniform magnetic field varying with time B 0 4t T is perpendicular to the plane of the ring Induced current in the ring is The ring will be in tension 2T 5 A The ring will be in compression The magnetic field due to ring at the center of the ring is in direction opposite to applied magnetic field

A uniform charge of 16 0 C is on a thin circular ring lying in an xy plane and centered on the origin The ring s radius is 3 00 cm If point A is at the origin and point B is on the z axis at z 4 00 cm what is VB VA

A wire 60 0 cm long is held parallel to and 100 cm above a long wire carrying 200 A and resting on the floor The 60 0 cm wire is released an falls remaining parallel with the current carrying wire as it falls What the induced emf on the wire 0 200 s after the wire is released Give your answer in V g 10 m s

For the hollow thin cylindrical current carrying pipe which statement is correct Question Type Single Correct Type 1 magnetic field inside the pipe is not zero 2 magnetic field outside the pipe is zero 3 electric field outside the pipe is zero

lons of two isotopes of K with masses 39 amu and 41 amu are accelerated in an electric field across 500 V and then injecte into a uniform magnetic field of induction 0 16 T perpendicular to the field Find the difference in the radii of the trajectories

A magnetising field intensity of 1000 A produces a m Wb m magnetic flux density 0 25 in a ferromagnetic substance The relative permeability of ferromagnetic substance is Approximately 2 0 104 2 0 10 4 0 10

A current carrying conducting circular arc which is making an angle 60 at its geometrical center is placed in a uniform transverse magnetic field as shown in the figure If radius of the arc is 50 cm current in the wire is A and magnetic field intensity is 2 T then the magnitude of magnetic force on the arc will be X X X XXXXXX X X X X X X X X XRX X X X X X 60 XXXX X X X X X X X 1 N 4 N 2 N Zero XX x x x X X X X X

180 3MB 2 A bar magnet of magnetic moment M is hung by a thin cotton thread in a uniform magnetic field Work done by the external agent to rotate the bar magnet from stable equilibrium position to 120 with the direction of magnetic field is consider change in angular speed is zero MB 2 MB Mark for MB 2 hr min

SAMPLE PROBLEM 32 2 A particular cyclotron is de signed with dees of radius R 75 cm and with magnets that can provide a field of 1 5 T a To what frequency should the oscilla tor be set if deuterons are to be accelerated b What is the maxi mum energy of deuterons that can be obtained

OPTIONS The active level to the CLR input and the Q outputs to verify all in their reset state CLR input at HIGH and the Q outputs are LOW CLR input at LO and Q outputs are LOW

or the hollow thin cylindrical current carrying pipe which statement is correc 1 magnetic field inside the pipe is not zero magnetic field outside the pipe is zero oloctric field outside the pipo is zoro electric field on the surface of pipe is zero 3 4

as mass 0 0160 kg and is 30 0 cm long It pivots without friction about an axis perpendicular nt a in Figure 1 The gravitational force on the bar acts in the y direction The bar is in a ic field that is directed into the page and has magnitude 0 250 B y X X X X X b X X 1 of 1 Part A T What must be the current I in the bar for the bar to be in rotational equilibrium when it is at an angle 30 0 above the horizontal Use the fact that 7 IBL for a uniform bar of length I carring a current I in a magnetic field Express your answer with the appropriate units I 0 84 Submit Part B Previous Answers Request Answer the right Incorrect Try Again 5 attempts remaining the left downward For the bar to be in rotational equilibrium should I be in the direction from a to b orb to a Drag the terms on the left to the appropriate blanks on the right to complete the sentences b n counterclockwise upward A clockwise www a Gravity tends to rotate the bar about point a so the magnetic force must be and to to tend Therefore the to rotate the bar current must flow from Reset Help could not balance to If the current were from to the bar

Two current carrying wire of infinite length are placed perpendicular to x y plane at x 0 and X R 3 as shown in figure Current in both the wires is same and 1 B del inwards to the x y plane Find ratio of segment CDA to segment ABC will be y A D I C R 3 B I X in

1 Column I shows graphs of electric potential V versus x and y in a certain region for four situations Colu Il shows the range of angle which the electric field vector makes with poisitive x direction Column l V versus x V versus y Column II Range of angle 45 30 45 0 90 NAC SIR A B C D 30 135 p r 0 0 45 90 0 135 s 135 0 180

A square loop ABCD of side length a and mass m is kept in a uniform magnetic field region B B as shown in the figure The loop is constrained to rotate only about the y axis It rotates only due to the torque of the magnetic force acting on it Calculate its angular speed when it has rotated through an angle 90 Initially the loop was lying in the x y plane The loop is carrying a current I as shown in the figure 31B Given O

c 3 6 10 NC d 4 6 x 105 NC 71 Consider a region inside which there are various types of charges but the total charge is zero At points outside the region a the electric field is necessarily zero b the electric field is due to the dipole moment of the charge distribution only c the dominant electric field is inversely proportional to r for larger distance from origin d the work done to move a charged particle along a closed path away from the region will not be zero 2 Two point charges of LuC and Con

na particle which is a positively charged particle enters a uniform magnetic field at rig ngles to it as shown below Stating the relevant principle explain in which direction will t particle move U Board Term 1 2016 a particle Magnetic field

A wooden bobbin consists of two coaxial of radius r and the outer is of radius R A conducting wire PQ wrapped on the outer cylinder passes through a small hole in it and then it is wrapped on the inner cylinder in the same sense Now the bobbin is placed on a horizontal table where a uniform and constant magnetic field B exists parallel to the axis of the bobbin If one end P of the wire is fixed on the tabletop and the other end Q is pulled horizontally with a constant velocity u as shown in the figure the bobbin rolls without slipping An ideal voltmeter is connected between the end P and a stationary sliding contact S mp P R SQ u a Find the moduli of electromotive forces induced in each of the coils 2 wrapped on the bobbin E Buf Ei Burz b Hence or otherwise find the reading of the voltmeter 2 R Y Bcllu