Magnetic Field Questions and Answers

Q 30 A charged particle is accelerated through a potential difference of 12 kV and acquires a speed of 100 m s It is projected perpendicularly into the magnetic field of strength 0 2 T The radius of circle described is cm

po 90 an mass m is entered into a magnetic field with velocity V as shown Uniform magnetic field is present only on right side of dotted line Average force exerted on charge particle during time it is inside magnetic field Right side A 2qBo Vo

Assertion A coil A is connected to a voltmeter V and the other coil B to an alternating current source If a large copper sheet C is placed between the two coils the induced emf in coil A is reduced Reason Copper sheet between the coils has no effect on induced emf in coil A A B C If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion If both Assertion and Reason are true but the Reason is NOT the correct explanation of the Assertion If Assertion is true but the Reason is false

Consider the diagrams shown Work done in transferring wire from position 1 to position 2 is W Work done in transferring the wire from position 3 to position 4 is W then Position 3 W W W 2 Position 1 Fixed Position 2 1 1 3 W W 0 Fixed Position 4

Example 4 10 The horizontal component of the earth s magnetic field at a certain place is 3 0 x105 T and the direction of the field is from the geographic south to the geographic north A very long straight conductor is carrying a steady current of 1A What is the force per unit length on it when it is placed on a horizontal table and the direction of the current is a east to west b south to north Solution F I1 x B F IIB sine PALDUAL CAMERA

Two bar magnets of magnetic moments 6 A m and 36 A x m are placed at 3 meter separation having common axis Magnetic force between magnets is 1 8 x 10 7 N 3 32 x 10 7 N 2 16 x 10 7 N 4 None

Please explain clearly Ans given is 3rd option 19 If a bar magnet moving towards the coil crosses the coil then current in the coil OL N 1 Increases 2 Decreases 3 First increases then decreases 4 First decreases then increases Asked by 2282292 aesl id Standard XII Stream NEET Jul 31 2021 at 1 08 AM Add your responses Type Text R Type your answer here OR you can upload an attachment from the option below

Four particles A B C and D of masses m ma me and m respectively follow the paths shown in the figure in a uniform magnetic field Each particle moving with same speed QA Q Qc and Qo are the specific charges of particles A B C and D respectively Constant

Magnetic field induction at the centre of a current carrying circular coil and a quarter circular coil of equal area is found to be equal in magnitude Find the ratio of current flowing in quarter circular coil and circular coil

Magnetic force on a spiral carrying current 10 and placed in magnetic field Bo parallel to the plane of spiral as shown in diagram will be nearly initial point final point and centre lie on a line lo 1111 Bo

A rectangular loop of area 0 4 m is lying in a magnetic field of 4 x 103 tesla If the plane of the loop is at right angles to the magnetic field then the magnetic flux passing through the loops will be A 1 6 10 weber 0 6 103 weber B C zero D 4x 10 weber

In the following figure the magnet is moved towards the coi with a speed v and induced emf is e If the magnet and coil recede away from one another each moving with speed v the induced emf in the coil will be O coil Xe 2 e e 2 NS

Consider a solid cylinder of radius R and very large length with uniform volume cha density p charge volume Cylinder is rotated with constant angular velocity abou axis Choose correct alternative s A Magnetic field at the axis of cylinder is zero B Magnetic field at the axis of cylinder is non zero C Magnetic field at a point outside the cylinder is zero D Magnetic field at a point outside the cylinder is non zero

toroid Using Ampere s law Derive an expression for magnetic induction at a point along the axis of a toroid 2 Derive an expression for the Energy stored in a magnetic field 3 The magnetic induction B and the magnetic intensity H in a material are found to be 15T and 1000 A m respectively Calculate the relative permeability and the monnata ANNUN

2 State Lenz s law and explain how magnet s motion creates a magnetic dipole in the coil 3 Define magnetic dipole moment for a current carrying circular coil 4 Explain why a copper disc swinging between the poles of a magnet comes to rest quickly

1 Figure shows an arrangement known as a Helmholtz coil It consists of two circular coaxial coils each of 200 turns and radius R 25 0 cm separated by a distance S R The two coils carry equal currents 12 2 mA in the same direction Find the magnitude of the net magnetic field at P mid way between the coils Y shue 20 P St a 8 7 x 10 6 T c 5 7 x 10 6 T R X b 6 7 x 10 6 T d 10 7 x 10 6 T

10 A current carrying closed loop in the form of a right angle isosceles AABC is placed in a uniform magnetic field acting along AB If the magnetic force on the arm BC is F then force on arm AC is a 2 F B b 2 F C F C d F

Section D Each Question carries 3 marks 9 1 What is a toroid Using Ampere s law Derive an expression for magnetic induction at a point along the axis of a toroid 2 Derive an expression for the Energy stored in a magnetic field

A long solenoid of 50 cm length having 100 turns carries a current of 2 5 A The magnetic field at the centre of the solenoid is Mo 4 x 10 7 Tm A NEET 2020 6 28 10 4 T 3 14 x 10 4 T 6 28 10 5 T

A straight wire of diameter 0 5 mm carrying a current of 1 A is replaced by the another wire of 1 mm diameter carrying the same current The strength of the magnetic field far away is 1999 1997 one quarter of the earlier value one half of the earlier value twice the earlier value same as the earlier value

A long solenoid carrying a current produces a magnetic field B along its axis If the current is doubled and the number of turns per cm is halved the new value of the magnetic field is 2003 B 2 B 2 B A D

A particle of mass 10 20 kg and charge 1 6 x 10 19 coulomb is moving in x direction with a velocity of 1 28 x 10 m s At time t 0 it enters a region of space where a uniform electric field Ex Ey 0 E 102 4 KV m and uniform magnetic field By B 0 By 8 x 10 2 T are present The resultant force on the particle will be 1 6 10 14 N 3 2 10 14 N 4 8 x 10 14 N Zero

In a mass spectrometer used for measuring the masses of ions the ions are initially accelerated by an electric potential V and then made to describe semicircular paths of radius R using a magnetic field B If V and B are kept constant the ratio to 2007 1 R R charge on the ion will be proportional mass of the ion

Bo 8 A current is flowing in a circular coil of radius R and the magnetic field at its centre is Bo At what distance from the centre on the axis of the coil the magnetic field will be O 7R O 3R O2R 8R

A positively charged particle moving due East enters a region of uniform magnetic field directed vertically upwards This particle will 1997 move in a circular path with a decreased speed move in a circular path with a uniform speed get deflected in vertically upward direction move in circular path with an increased speed

of kinetic energy 50 keV is A deuteron describing a circular orbit of radius 0 5 metre in a plane perpendicular to magnetic field B The kinetic energy of the proton that describes a circular orbit of radius 0 5 metre in the same plane with the same B is 1991 25 keV 50 keV 200 keV 100 key

A beam of electron passes undeflected through mutually perpendicular electric and magnetic fields If the electric field is switched off and the same magnetic field is maintained the electrons move 2007 in a circular orbit along a parabolic path along a straight line in an elliptical orbit

A short bar magnet is kept in uniform magnetic field of 0 16 T such that dipole moment vector is at angle 30 with the field The torque acting on the bar magnet is 0 032 N m What is magnitude of magnetic dipole moment of the magnet

Consider a heat engine as shown in figure Q Q2 are heat added to T and heat removed from T2 in one cycle of engine W is the mechanical work done on the engine If W 0 then which statement is true T 1 2 Question Type Single Correct Type 3 Q2 Q1 W Q W Q2 Q1 Q T

The magnetic force acting on a charged particle of charge 2 C in a magnetic field of 2 T acting in y direction when the particle velocity is 21 3 x106 ms lis 2009 4 N in z direction 8 N in y direction 8 N in z direction 8 N in z direction

A long straight wire carries a certain current and produces a magnetic field 2 x 10 4 Wb m at a perpendicular distance of 5 cm from the wire An electron situated at 5 cm from the wire moves with a velocity 107 m s towards the wire along perpendicular to it The force experienced by the electron will be charge on electron 1 6 x 10 9 C Karnataka Neet 2013 3 2 N 3 2 10 16 N 1 6 10 16 N

In the figure shown two blocks of equal mass m are connected by an ideal string that passes over an ideal pulley The blocks are connected by springs of force constants k and k2 k1 Initially both the springs are relaxed Then the left block is pulled down a distance x and released Magnitudes of accelerations of the left and the right blocks immediately after release are a and a 2 respectively Then 0000000000 xxxxxxxxxx SAT

C 0 15N Figure shows a spherical gausion sur charge distribution when calculating the flux of electric field through the gaussion surface the electric field will be due to A q3 along C q1 q3 and q2 ql q2 g3 B ql and qs D q1 and q2

a In figure a the radii a and b as well as the angle o are known P b In figure b the radius a and the side b are known c A current I 5 0 A flows along a thin wire shaped as shown in figure The radius of a curved part of the wire is equal to R 120 mm the angle 2p 90 Find the magnetic induction of the field at the point O

Two concentric circular loops of radii r 7 cm and r 14 cm are placed in the Y Z plane as shown in the figure The magnetic moment of this loop system is 55 10 Am 55 10 Am 33 x 10 Am 33 10 Am 10 A 5A

A positive point charge q is carried from a point B to a point A in the electric field of a point charge Q If the permittivity of free space is E the work done in the process is given by a G 90 4 La b 90 11 2 B 92 11 47 E La b 92 1

A conducting rod of length is moved at constant velocity vo on two parallel conducting smooth fixed rails that are placed in a uniform constant magnetic field B perpendicular to the plane of the rails as shown in figure A resistance R is connected between the two ends of the rail Then which of the following is are correct R www A 8 x B X B The thermal power dissipated in the resistor is equal to rate of work done by external person pulling the rod If applied external force is doubled than a part of external power increases the velocity of rod C Lenz s Law is not satisfied if the rod is accelerated by external force V If resistance R is doubled then power required to maintain the constant velocity vo becomes half

A region contains both uniform electric field E and uniform magnetic field B A charged particle a Cannot move on a circular path in this region b Cannot move on a uniform helical path c Cannot move on a parabolic path d All of these

A uniform rod of mass M and length L carrying a charge q uniformly distributed over its length is rotated with constant velocity w about its mid point perpendicular to the rod Its magnetic moment is

The charge carriers are moving from left to right in the magnetic field which is into the page and point S is at higher potential then the charge carrier are X X X 3 X X XX 1 negative 2 positive neutral X X X X X X X X X S Question Type Single Correct Type P X X X X X X

ght net tio ht of and ns to E perpendicular to the plane of the paper produces a magnetic field as shown in the figure A square of side a is drawn with one of its vertices on the centre of the wire The integral Bdr along OPORO has the value 1 Hol 31

R A solid cylindrical wire of radius R carries current distributed uniformly over its cross section The magnetic field at a distance from the axis 2 of the wire will be Hol 2x R Hol 4 R Hol TR Hol 2R

In the given circuit ABCD is a square of side a If magnetic induction at point O is find the value of N Dotted line represents that wire goes upto infinity 21 B 21 21 41 Nuk 2 1 2x8

Figure shows three arrangements of electric field lines In each arrangement a proton is released from rest at point A and is then accelerated through point B by the electric field Points A and B have equal separations in the three arrangements If P P and P3 are linear momentum of the proton at point B in the three arrangements respectively then A B 1 a P P3 P c P P P A B A 2 b P P P3 d P P P 3 B

The electric field strength on the axis of the cylinder length L radius R at a point P whose distance from nearer face of the cylinder is r is P L R r L R P 280 2 20 L R p R R L 1 3 200 R r L R r PR

As we go from the magnetic equator towards the geographic south pole the angle of the dip will become 1 More and more vertically downward and perpendicular to the surface at the magnetic pole 2 More and more vertically upward and become perpendicular to the surface at the magnetic pole 3 Less and less vertically downward and become horizontal at the magnetic pole 4 Less and less vertically upward and become horizontal at the magnetic pole

Magnetic flux through a surface of area A placed in a uniform magnetic field is given by 0 is angle between and A BA sin 0 BA cos 0 BA cose BA sin 8

The direction of induced current is such that it opposes the cause that has produced it This law is given by Lenz Faraday Kirchhoff

A pair of adjacent coils has a mutual inductance of 1 5 H It the current in one coil changes from 0 to 20 A in 0 5 s what is the change of flux linkage with the other coil 30 Wb 33 Wb 23 Wb 42 Wb

I A t s 0 1 Magnetic flux changes in a coil of resistance 10 Q As a result an induced current is developed in it which varies w time as shown in figure The magnitude of change in flux through the coil in weber is 4 8 hr m 2