Magnetic Field Questions and Answers

A particle mass 2 0 mg q 6 0 C moves in the positive direction along the x axis with a velocity of 3 0 km s It enters a magnetic field of 3 0j 4 0k mT What is the acceleration of the particle a 36j 27k m s 2 0i b 36j 27k m s c 24j 18k m s d 24j 18k m s e 24j 27k m s C

3 88 cm 4 8 8 cm 56 A negatively charged particle mass m charge q is thrown with speed v along x axis in a region of uniform magnetic field B directed along positive z axis If thickness of the region is particle as it comes out of the magnetic field mv qB find angular deviation in path of the 1 8 sin dqB mv 2 9 sin dqB 2mv

1 iL B K 2 iL B K 3 2iL B K 4 2iL B K 58 An alpha particle and a proton are projecte normally into uniform magnetic field with same kinetic energy Radii of their path is 2 1 2 4 2 2 1 1 1 59 3 2 1 eetquestion per A flexible wire loop carrying a current I is placed in

3 A short solenoid of radius a number of turns per a very long solenoid of radius b number of turns per unit length n and length L is kept coaxially inside unit length 1 What is the mutual inductance of the system a b n L c n n L b a n n L d b n n L 88

3 6 mg 2 mgl 4 3 mg 5 mgl A projectile of mass m is fired with velocity V 20 from a point P as shown the magnitude of the change in momentum between the points P and arriving at Q is 1 0 P450 Q 2 mY 3 mV 2 4 2 mV ing at 20m s at its highest 21 3 6 mg 2 mgl starfa fan atat p an adam 1 0 P 45 4 3 mg 5 mg van pf fange V mV 2 Q 2 3 mV 2 4 2 m 20m s

Two concentric circular loops of radii 0 08m and 0 1m carries current such that magnetic field at the centre is zero If the current in the outer loop is 8A clockwise current in the inner loop is 1 6 4 A anticlockwise 2 6 4 A clockwise 3 8A anticlockwise 4 3 2 A clockwise 19

Two infinite long parallel wires carry equal currents in same direction The magnetic field at a mid point in between the two wire is 1 Twice the magnetic field produced due to each of the wires 17 2 Half of the magnetic field produced due to each of the wires 3 Square of the magnetic field produced due to each of the wires

9 If an electron of velocity 2 1 3j is subjecte to magnetic field of 4k then its a path will change b speed does not change c path must be circular d momemtum is constant 1 a b 2 All 4 none

40 PQ and RS are long parallel conductors separated by certain distance M is the midpoint betwee them The magnitude of net magnetic field at M is 2B Now the current 1 A is switched off Then th magnitude of the field at M now becomes 2 2A M R S 1A

An infinitely long current carrying wire carrying current I is present at origin perpendicular to xy plane A quarter circular conducting wire carrying current I of radius 3a is placed in xy plane between the points A and B as shown A 3a B 3a Any The magnitude of magnetic force acting on the quarter circular wire is K Holl Where K T Take In 5 1 601

Read More A rectangular loop carrying a current i is situated near a long straight wire such that the wire is parallel to one of the sides of the loop and the plane of the loop is same of the wire If a steady current is established in the wire as shown in the figure the loop will Rotate about an axis parallel to the wire Move away from the wire Move towards the wire

A long straight wire carrying a current of 1 0 A is placed horizontally in a uniform magnetic field B 1 0 x 105 T pointing vertically upward figure The magnitude of the resultant magnetic field at the points P and Q both situated at a distance of 2 0 cm from the wire in the same horizontal plane are respectively P Q O zero 20 T 20 T zero BO zero zero O 20 T 20 T Marks 4 1

Following is square shape loop whose one arm BC produces magnetic field B at the centre of coil The resultant magnetic field due to all the arms will be 1 4B 2 B 2 3 B 42B O HB 6 7 MG0002

A magnet is placed co axially with the conducting loop A when the magnet is pushed towards right a clockwise current is observed Bif the flux passing through the loop is and its resistance is R the total charge flown after the magnet is thrown to infinity is if the loop s resistance is neglected and inductance is assumed to be L the flux passing through th loop is conserved if we bring the resistanceless loop from infinity it will carry a current i induntance of the loop and p flux passing through the coil by the magnet whe wh

8 A metallic rod CD rests on a thick metallic wire PQRS PQ X X X X X with arms and RS parallel to each other at X a distance 1 40 l 40cm 3 X cm as shown in Hint T X X 10 X XBX X C X X figure A uniform magnetic X X field B 0 1 Tacts perpendicular to the plane of this paper pointing inwards i e away from the reader The rod is now made to slide towards right with a constant velocity v 5 0 ms i How much emf is induced between the two ends of the rod CD ii What is the direction in which the induced current flows ISC 2013 10 v M X X D X X X P S

43 A current i ampere flows in a circular arc of wire whose radius is R which subtend an angle 31 2 radian at its centre The magnetic induction B at the centre is 1 Hoi R 2 Hoi 2R 3 2 i R 4 3 i 8R

2 Two parallel long wires carry currents i and i with i i When the current are in the same direction the magnetic field at a point midway between the wires is 10 T If the direction of i is reversed the field becomes 30 T Then the ratio i i2 is 1 4 2 3 3 2 4 1

A current i is flowing in a conductor shaped as shown in the figure The radius of curve part is r and length of straight portions is very large The value of magnetic field at the centre will be A Ho 3 1l o i

Find the value of r for which magnetic field at point P on the axis of a circular current carrying loop of radius a is maximum as shown in figure 1 r 2 3 r 2a r SP 2 r 1 2 4 r 0

The length of a long straight solenoid is 10 cm and the number of turns in it is 200 If 1 A current flows through it determine the magnetic field at any point on the axis of the solenoid 144 2 5 10 3 T

4 The radius of the first electron orbit of a hydrogen atom is 0 5 The electron moves in this orbit with a uniform speed of 2 2 x 106ms What is the magnetic field pro duced at the centre of the nucleus due to the motion of this electron 14 08 T

12 A loop of wire carrying a current is placed in a uniform magnetic field as shown then O N a C b d S 1 point The side ad experiences a force into the page The side ab experiences a force into the page The side cd experiences a force into the page The side cd experiences a force to the right

13b If 50 0cm of copper wire of diameter 1 00mm is formed into a circular loop and placed perpendicular to a uniform magnetic field that is increasing at the constant rate of 10 0 mT s at what rate is thermal energy generated in the loop

n the figure below the current in the long straight wire is I 6 80 A and the wire lies in the plane of the rectangular loop which carries a current I 10 0 A The dimensions in the figure are c 0 100 m 0 150 m and l 0 560 m Find the magnitude and direction of the net force exerted on the loop by the magnetic field created by the wire magnitude N direction Select V 1

A ring of radius R rotates with a constant angular velocity w about an axis passing through center and perpendicular to its plane The ring is in x y plane The potential difference induced in the ring would be zero if uniform magnetic field is along Ox axis O y axis O z axis G

A superconducting ring has a radius R 20 cm and mass M 31 4g The ring carries a constant current i and is placed in a magnetic field B 0 5 T with field line titled at an angle 30 outwards from the vertical at every location around the ring as shown Find the current i in A for the ring to float in magnetic field g 10 m s and n 3 14 Ho

The figure shows certain wire segments joined together to form a coplanar loop The loop is placed in a perpendicular magnetic field in the direction going into the plane of the figure The magnitude of the field increases with time I and 12 are the currents in the segments ab and cd Then IIT JEE 2009 d X X X X X axb X X X X X X X X X X X a 1 1 b 1 1 c I is in the direction ba and I2 is in the direction cd d I is in the direction ab and I is in the direction de X potential b 2rBu and R is an c Zero d Buzr 2 and potential A charged particle is cm with a uniform spe a uniform magnetic fie the plane of the orb particle is a 5x10 C kg c 5x10 C kg An electron moves in a

A metallic square loop ABCD is moving in its own plane with velocity v in a uniform magnetic field perpendicular to its plane as shown in the figure An electric field is induced in A O O O O D B A AD but not in BC B O BC but not in AD O O C Neither in AD not in BC D O Both in AD and in BC

A straight wire carries current in vertical upward direction A point P lies just east of it at a small distance an another point Q lies to the west just same distance The magnetic field at these points consider earth magnetic field 1 Bp Ba 3 Bp Bo 2 Bp Bq 4 None

A cavity is taken out from a uniform conducting sphere Inside the cavity a dipole is placed as shown in the figure Find which of the following is are true Given q 10 1c t 0 1 mm 0 30 d 10 cm R 12 cm P 18 Potential at points A B are same Potential at points A B are different Potential at point P is 0 volt Potential at point P is 2 volt q O B 130 d R A 4

4nd Illustration 5 If point P lies out side the line of wire then magnetic field at point P will be olution Bp 4nd Hol 4nd HOI sin 90 a sin 90 a cosa cosa 4nd a2 d 90 0 90 a P

6 The period of oscillation of compass needle is 8 s at a place where dip angle is 30 and magnetic field is B another place where dip angle is 60 and magnetic field is B the period of oscillation is 4 s then B is B 1 4 3 2 3 3 3 5 7 4 87 Nou Delhi 110005 Ph 011 4762345

Same current is flowing in three infinitely long thin wire along positive x y and z direction The magnetic field at a point 0 0 a would be i 1 OH i i O 2ra Ho i k

A non relativistic beam of protons passes without deviation through the region of space where there are uniform transverse mutually perpendicular electric magnetic and fields E and B respectively are present Then the beam strikes a grounded target If the beam current is I then the force exerted by the beam on the target is q is the charge on proton and m is mass 1 F 3 F mIB qE 1932 2 mIB gE 2 F mIE by qB 4 F 2 mIE qB

6 A bar magnet and a wooden bar identical in dimension and mass are released from same height to fall under gravity passing through multiple rings of conducting material Time taken by bar magnet is T and by wooden bar is T2 Then which is possible out of given options 1 T T 2 T T 3 T T 4 None of these

A horizontal rectangular surface has dimensions 2 8 cm by 3 2 cm and is in a uniform magnetic field that is directed at an angle of 300 above the horizontal What must be the magnitude of magnetic field be in order to produce a flux of 4 2 x 10 4 Wb a 0 45 T b 0 54 T c 0 5 T d 0 52 T

A proton makes a full rotation in a circle of radius 0 4 metre in two seconds The value of the magnetic field B at the centre of the circle will be 4x102T O 2x100 T 4x10 2 T 2x10 2 T

A coil of a moving coil galvanometer has 100 turns and effective area of 0 05 m It is suspended in a radial magnetic field of induction 0 01 Wb m The torque per unit twist of the suspension fibre is 5 x 10 Nm degree What is the current sensitivity of the moving coil galvanometer A 105 degree ampere YOU B C 107 degree ampere 2 x 106 degree ampere

Consider two infinitely long wires parallel to Z axis carrying same current I in the positive Z direction One wire passes through the point L at coordinates 1 1 and the other wire passes through the point M at coordinates 1 1 The resultant magnetic field at the origin O will be B 2 2 A Ho Holi 2 C Holi 2 2T D Holi 4

ight infinitely long current carrying wires are kept along z axis at the coordinates 0 a 0 and 0 a 0 respectively as shown in the figure The current in each of the wire is equal and along negative z axis into the plane of the paper The variation of magnetic field on the x axis will be approximately B B a c B X X b d a a B X

The frame is a combination of two equilateral 32 Same current i 2 A is flowing in a wire frame as shown in triangles ACD and CDE of side 1 m It is placed in uniform magnetic field B 4T acting perpendicular to the plane of frame The magnitude of magnetic force acting on the figure frame is Magneti X X X X x C X bell X A BE DIGIT 24 N b zero c 16 N X More than 1 Two cir of 2 A are pla centr com a t d 8 N They

Field the d 8 N 33 Two long parallel wires are at a distance 2d apart They carry steady equal currents flowing out of the plane of the paper as shown The variation of the magnetic field B along the line XX is given by a c X ingg B U 13th B ton d d I 16 N X b X X d X B Ko B B d d X 34 Two charged particles traverse identical helical paths in a

89 Agiven length of a wire carries a steady current It is bent first to form a circular plane coil of one turn If a loop of same length is now bent more sharply to give a double loop of smaller radius the magnetic field at the centre caused by the same current is a a quarter of its first value b unaltered c four times of its first value d two times of its first value Miscellaned 96 Magnetic eff a Faraday fc Ampere 97 One tesla i a 10 gaus c 10 gau

Problem 1 How many poles are in the right half plane in the left half plane and on the ju axis for the following function T s s 4s 3 s4 453 8s 20s 15

A particle of charge q and velocity v passes undeflected through a space with non zero electric field E and magnetic field B The undeflecting conditions will hold if a signs of both q and E are reversed b signs of both q and B are reversed c both B and E are changed in magnitude but keeping the product of B and E fixed d both B and E are doubled in ma

3 0 105 4 Zero 10 Charges Q 2Q and 4Q are uniformly distributed 10 in three dielectric solid spheres 1 2 and 3 of radii R 2 R and 2R respectively as shown in figure If magnitudes of the electric fields at point P at a distance R from the centre of spheres 1 2 and 3 are E E and E respectively then 11 20 R 2 40 Sphere 2 Sphere 3 2 E E E 4 E E E 28 Sphere 1 1 E E E 3 E E E An electron moves on a straight line path XY as 11 3 0 105 Q 20 i 40 R2 R2R 12 a eu faaka tafe 1 23 Rafa E at Sphere 1 1 E E E 3 E E E agia and Sphere 2 O 2R Sphere 3 2 E E E 4 E E E XY

c the R energy the momentum d None of these proton moves at a speed v 2x10 in a region of constant magnetic field of magnitude B 0 05 T The direction of the proton when it enters this field is 0 30 to the field When you look along the direction of the magnetic field the path is a circle projected on a plane perpendicular to the magnetic field How far will the proton move along the direction of B when two projected circles have been completed 201 a 4 35 m c 2 82 m b 0 209 m d 2 41 m a b 39

93 In a coaxial straight cable the central conductor and the outer conductor carry equal currents in opposite directions The magnetic field is zero a outside the cable b inside the inner conductor c inside the outer conductor in between the two conductors 195

ons of two isotopes of K with masses 39 amu and 41 amu are accelerated in an electric field across 500 V and then injected to a uniform magnetic field of induction 0 16 T perpendicular to the field Find the difference in the radii of their K qv rajectories mu 2m k h 2 mq v 0r 22 ab AB 93

uniformly charged semi infinite conducting wire is placed along x axis as shown in figure such that one end at the origin Then electric field intensity at the point P will be Where is linear charge density of wire 1 3 P 0 a 4 2 ATS 2 4 ATC 2 2 4 4 00 4 2 Arc