Magnetic Field due to current Questions and Answers

e 12 A current carrying conductor of length I is bent into two loops one by one First loop has one turn of wire and the second loop has two turns of wire Compare the magnetic fields at the centre of the loops 1 In first Case 2 r At centre B B B 2r 12 B 4B Mol 20 4 In second case 2 x 2 r r 12 B 2x oi 212 there are 2 turns M centre of the loop Moi 2h Ti

A conductor carrying a current I has three seg ments as shown What is the magnetic field B at the centre of curvature C of the semicircle A C Ho I 4T R Ho I 4 R 1 TIL B C D Mo I 4 R R Hol 4 1 TLA 1

5 A long wire carries a steady current It is bent into a circle of one turn and magnetic field at the centre of coil is B It is then bent into a circular loop of n turns The magnetic field at the centre of coil for same current is 1 nB 3 2nB 2 n B 4 2n B

SolveLancer Test A coil consisting of 400 turns is rotated with an angular velocity of 600 rpm in a magnetic field of magnitude 0 4 mT about a diameter normal to the field The resistance of coil is 8 and its area is 80 cm Find the average emf developed in half a turn from a position where the coil is normal to the magnetic field SolveLancer Test a b c d 51 2 mV 25 6 mV 38 4 mV 31 2 mV

SolveLancer Test The world s biggest aircraft Antonov AN 225 Mriya has an approximate wingspread of 100 m It travels from Ukraine in the east direction with a speed of 200 ms When it flies over a particular city the earth s total magnetic flux density is observed to be 0 4 mT and the dip circle on the aircraft measures the dip angle at that place as 60 The potential difference developed across the ends of the wings is SolveLancer Test a 4 00 V b 6 93 V c 3 47 V d 1 73 V

A conducting ring of mass m and radius r has a weightless conducting rod PQ of length 2r and resistance 2R attached to it along its diameter It is pivoted at its centre C with its plane vertical and two blocks of masses m and 2m are suspended by means of a light in extensible string passing over it as shown in the figure The ring is free to rotate about C and the system is placed in a magnetic field B into the plane of the ring A circuit is now completed by connecting the ring at A and C to a battery of emf V Find the value of V in Volts so that the system remains static Take m 100 kg B 100 Tesla r 20 X P X X X X m X X A O X X X X 2m Resistance of PQ 2R

Test 4 Code A 38 A capacitor of capacitance C is connected to a V volt potential Battery is then disconnected and inductor of inductance L is connected across the capacitor so that LC oscillations are set up The maximum current in the coil is C 1 3 V 1 3 4 39 The inductance of a closed packed coil of 400 turns is 8 mH A current of 5 mA is passed through it The magnetic flux per turn is Hg Permeability of free space 1 2 3 4x Ho Wb 1 3x 2L Ho Wb 4 0 4 Wb 40 A coil having n turns and resistance R is connected with a galvanometer of resistance 4R The combination is moved in time t such that magnetic flux per turn changes to flux 2 per turn The average induced current in the circuit is 5Rnt n 0 0 5Rt Rnt n Rt 2 2 v C 2VZ w dxxx 2x 4 41 A massless square loop of side carrying current i is suspended from a pulley as shown in the arrangement Lower edge of the loop is in transverse magnetic field B The minimum current i required in the loop to just move the block of mass m up the inclined plane is 2C Wb 3 42 1 2 3 4 Aakash Rank Booster Test Series for NEET 2020 mg sine mg cos BI 2 mg sine mg cose 2B 2mg sine 2 mg cose BI A conducting loop is placed in a magnetic field of strength B perpendicular to its plane Radius of loop is r current in the loop is i and linear mass density of loop is m Speed of any transverse wave in the loop will be 3 mg sine mg cos BI Bir m 2Bir m 2mv qE 3 43 A particle of charge q and mass m starts moving from origin under the action of an electric field Ei and B B with velocity v v The time after which its speed becomes 2v is 28 9 mvo 38 9 mvo 2 3 mv qE Bir 2m 4 2 Bir m 44 A conducting circular loop of radius r carries a constant current i It is placed in uniform magnetic field B such that B is perpendicular to plane of the loop Find the magnetic force acting on the loop 1 irB 2 2rriB 4 TriB 3 Zero 45 If current is passed in a spring then it 1 Gets compressed 2 Gets expanded 3 Oscillates 4 Remains unchanged

two A long cylindrical iron core of cross sectional area 5 cm is inserted into a long solenoid having 2000 turns and carrying a current 2A The magnetic field inside the core is found to be 1 57 tesla Neglecting the end effect the pole strength developed 1 325 A m 2 625 A m 3 125 A m 4 425 A m

44 A current loop of area 0 01 m and carrying a 2 current of 10 ampere is held perpendicular to a mag netic field of intensity of 0 1 tesla The torque in N m acting on the loop is a 0 c 0 01 b 0 001 d 1 1 CBSE PMT 1994

zero dip c zero declination d equal declination mig lasinsv nols onil Two magnets have the same length and the same pole strength But one of the magnets has a small hole at its tomonsvleg nogosts 6 centre Then vom a both have equal magnetic moment b one with hole has smaller magnetic moment c one with hole has larger magnetic moment d one with hole loses magnetism through the hole

0 4 1 8 10 H A conducting rod AC of length 41 is rotated about 40 a point O in a uniform magnetic field B directed into the paper AO 1 and OC 31 Then X X X X X X X 1 VA Vo X Bol 2 X 7 2 Vo Vc Bol 3 VA Ve 4Bol 4 Ve Vo Bol o Bo 0 X C X 4 1 8 x 102 H X X X 1 V V un Bol 2 2 Vo Vc Bol 3 VA V 4Bol 4 Vc Vo Bol AC gi A131 X 0 X

16 Two wires AO and OC carry equal currents i as shown in figure One end of both the wire extends to infinity Angle AOC is a The magnitude of magnetic field at a point P on the bisector of these two wires at a distance r from point O is a oot Hoi 2 r c HQ 1 cos2 2Tr a A P C b Ho i 4 r cot 9 Ho d sin 4 r 2

parabola 25 A conducting wire bent in the form of a y 2x carries a current i 2A as shown in figure This wire is placed in a uniform magnetic field B 4k tesla The magnetic force on the wire is in newton 16i y m 321 A 12 0 B x m c 32i d 16

Find the flux passing through the shaded rectangular plane which passes through the axis due to the long straight current carrying conductor having a current i Given length 1m current I 2A Radius in weber Write value of n R 5cm If answer is n Hol 1 16 R

X axis Two wires of same length are shaped into a square and a circle If they carry same current ratio of the magnetic moment is MINI 1 2 n 2 x 2 3 4 4 4 T NTHUSE LEADER ACHIEVER ALPHA PLUS SPARK GRAS 14082021

If current I flows through a closed loop as shown then the magnetic field at the centre O is Only one correct answer R 20 6 0 sin 0 440 I 2x R B C PO I 2 R 0 sin 0 I C 2m 0 sine po 1 T A tan A

5 A circular coil of 0 2 m diameter has 100 turns and carries a current of 0 1 ampere The intensity of magnetic field at the centre of the coil is a 6 28 10 4 N A m c 6 28 10 5 N A m b 62 8 x 10 4 N A m d 62 8 x 10 5 N A m

A current i is uniformly distributed over the 27 cross section of a long hollow cylindrical wire of inner radius R and outer radius R Magnetic field B varies with distance r from the axis of the cylinder as 3 B4 114 2 B4 RARE GRA accurates freen R an art fR ta ha Ba 3 ra hai niem 147 D Y 194 The following statement is false for Helmholtz 28 teater quaferat af coils DA fra feri

4 53 A closed curve encircles several conductors The line integral B di around this curve is 3 83 x 10 7T m a What is the net current in the conductors b If you were to integrate around the curve in the opposite direction what would be the value of the line integral

4 9 A charge of 1 coul is placed at one end of a non conducting rod of length 0 6m the rod is rotated in a vertical plane about a horizontal axis passing through the other end of the rod with angular frequency 104 T radian sec Find the magnetic field at a point on the axis of rotation at a distance of 0 8 from the centre of the path Now half of the charge is removed from one end and placed on the other end The rod is rotated in a vertical plane about horizontal axis passing through the mid point of the rod with the same angular frequency Calculate the magnetic field at a point on the axis at a distance of 0 4m form the centre of the rod

3 Zero 4 28 In the given figure there is current carrying straight wire of infinite length having current i A rod of length is coplanar with the wire and perpendicular to it If the rod moves with constant velocity v then the induced emf in the rod Tax Hoi vin a t MO viln 2 a a 2T

process A circular loop of radius 4 cm and carrying current 0 2 A is placed in a uniform magnetic field of induction 0 4 T and perpendicular to the plane of the loop Calculate the force on the arc of the circle of length 4 3 cm non of radius R carries a

ion e 40 A cylindrical a constant current The plot of the magnitude of the magnetic field B with the distance d from the centre of the conductor is correctly represented by the figure here curre current resent B n a B assing nough 8 c sect parea R d b d B B R d R d to consider if nothing

SolveLancer Test A student uses a copper conductor XY of length 100 cm and moves it in a magnetic flux density of magnitude B 0 05 T with a speed 12 ms 1 as shown in the figure Calculate the emf produced and power dispensed if resistance of circuit is 0 2 0 B X 100 cm

1 27 A 2 54 A 3 108 A 4 054 A 9 A hollow cylinderical wire carries a current 1 having inner and outer radii R and 2R respectively Magnetic field at a point which 3R 2 distance away from its axis is 1 3 2 0 18TR 5 I 2 4 Hol 36 R 5 ol 9TR

Read More The magnetic force acting on a charged particle having charge 2 C in a magnetic field of 2 T acting in y irection moving with velocity 21 3 x 106 m s is O4 N in z direction O 8 N in y direction O 8 N in z direction O 8 N in z direction

44 The total flux associated with the given cube will be where a is side of the cube 5 ST 4 9 10 SI units A 162 x 10 3 Nm C 3 162 x 10 Nm C 162 x 10 6 Nm C 162 x 106 Nm C 4 C 2 C 6 C 8 C a a 1 C 3 C a 7 C 5

Find the magnitude of the magnetic field induction at the origin O due to a very long conductor carrying current i of the shape shown in figure 1 2 3 4 Ho 2r Mol 2r Hol 4 r Ho 1 12 X

R Problem 1 8 A thin insulated wire form a spiral of N 100 turns carrying a current of i 8mA The inner and outer radii are equal to a 5cm and b 10cm Find the magnetic field at the centre of the coil Solution Let n no of turns per unit length along the radial of spiral Consider a ring of radii x and x dx N ndy n

A 4 pole d c shunt motor has a flux per pole of 0 04 Wb and the armature is lap wound with 720 conductors The shunt field resistance is 240 2 and the armature resistance is 0 2 2 Brush contact drop is 1V per brush Determine the speed of the machine when running a as a motor taking 60 A and b as a generator supplying 120 A The terminal voltage in each case is 480 V A 4 pole d c shunt motor has a wave wound armature with 65 slots each containing 6 conductors The flux por pola is 20 mWh and the has a resistance of 0 15

A wheel of mass M and radius r having charge Q uniformly distributed over its rim is rolling on rough horizontal ground without slipping about a light rod of length 2L A uniform magnetic field B directed opposite to the gravitational field is switched on in the space Find the value of mass m that should be placed at the end of rod to prevent the toppling of wheel 10 P CXO

11 An insulating rod of length 1 carries a charge q distributed uniformly on it The rod is pivoted at an end and is roated at a frequency f about a fixed perpendicular axis The magnetic moment of the system is 1 zero 2 qfl 3 nqfl 4 nqfl

A positively charged particle P crosses a region of uniform electric fie of intensity E Velocity u of the particle at the entry on the left side the region is perpendicular to the electric field as shown in the fir figure Speed of the particle at exit on the right side is U Now t experiment is repeated with a uniform magnetic field of induction superimposed on the electric field as shown in the second figure keepi entry velocity of the particle unchanged In this experiment speed of t particle at exit on the right side is U What can you conclude regard the speeds U and v d If u c If u B E B 9 then then U U U U If u d If u E B E B 2 2 then U U1 then U U

A square loop ABCD carrying a current i is placed near and coplanar with a long straight conductor XY carrying a current I the net force on the loop will be 2uolil a b 3m 2 gli 3T c d Molil 2 Moli 2 NEET I 2016

4X A straight conductor carrying current i splits into two parts as shown in the figure The radius of the circular loop is R The total magnetic field at the centre P of the loop is NEET 2019 Odisha Hol 1 2R 2 Zero 3 3 i 32R outward inward 90

A circular coil is in y z plane with centre at origin The coil is carrying a constant current Assuming direction of magnetic field at x 25 cm to be positive direction of magnetic field which of the following graphs shows variation of magnetic field along x axis a c B to 0 d B B 0 X

0 Two equal electric currents are flowing perpendicular to each other as shown in the figure AB and CD are perpendicular to each other and symmetrically placed with respect to the currents Where do we expect the resultant magnetic field to be zero C 11 A a On CD b On AB c On both OD and BO d On both AB and CD B a D 1006

For the magnetic field to be maximum due to a small element of current carrying conductor at a point the angle between the element and the line joining the element to the given point must be 1 0 2 90 3 180 4 45

A long straight conductor carrying current I is fixed on a smooth plane A circular loop is placed on the same plane as shown in the figure If the current I through the wire is increasing then the loop will move towards 1 Right 2 Left 3 Up 4 Down O

A conducting rod of length L rotating in x z plane with constant angular velocity about an axis yy in an uniform magnetic field B as shown in the figure The emf Induced between the ends P and Q at the instant shown will be y 3x B B k X 3 X L 4 1 Zero BL 2 X 34x 4 X 2 4 Q X BL 0 4 10 X BL

Two co axial rings of same radius R 10 cm are placed parallel to the y z plane such that x axis is the axis of the rings Ring 1 carries a current of 2 Ampere and ring 2 carries a current of 1 Ampere as shown in the figure The separation between the rings is d 50 cm Find the magnitude of B dx where B 440 is the net magnetic field at any point on the axis Current in both the rings are in opposite sense Ring 1 Ring 2 Oro

A circular loop has a radius 20 cm is placed in a uniform magnetic field B 2T in the XY plane as shown The loop carries current i 1A The magnitude of torque acting on the loop is 1 0 25 N m 1 5 2 N m 3 2 5 N m 4 052 N m 450 B X

Wires 1 and 2 carrying currents i and 12 are inclined at an angle to each other What is the force on a small respectively element dl of wire 2 at a distance of r from wire 1 as shown in figure due to the magnetic field of wire 1 2 Ho 2 r 8 dl Ho a ii2dl tan 0 2 r Fii2dl sin 0 C Ho Ho 2 r indl sin e apd i1i2dl cos 0 b d

A thin walled hemispherical shell of mass m and radius R is pressed against a smooth vertical wall Through a very small aperture at its top water of density p is filled in it completely Minimum magnitude of force is to be applied to the shell for liquid not to escape from it Weight of 2 hemispherical shell is mg and total mass of water is M R p

An elastic conducting cord of length lo and force constant k is fastened to two nails N and N as shown Unif magnetic field B is present as shown If constant current is passed through cord then in steady state N A B C D X B N Shape of cord would be circular arc Shape of cord would be parabolic arc Shape of cord would be elliptical arc Magnetic force of cord is lloB

View In English In the figure a charged sphere of mass m and charge q starts sliding from rest on a vertical fixed circular track of radius R from the position shown There exists a uniform and constant horizontall magnetic field of induction B The maximum force exerted by the track on the sphere is 2 3 ect Answer 3 Answer 4 mg 3mg qB 2gR 3mg qB 2gR mg qB 2gR m B

29 A long straight wire of radius a carries a steady current I The current is uniformly distributed over its cross section The ratio of the magnetic fields B and B at radial distances and 2 a respectively from the a 2 axis of the wire is 1 los a 2 LOT c 4 d

Three long straight and parallel wires carrying current are arranged as shown in figure The force experienced by 10 cm length of wire Qis R Q P 2 cm 20 A 10 A 10 cm 30 A O 1 4 x 10 4 N towards right 1 4 x 10 4 N towards left 2 6 x 10 4 N towards left 2 6 x 10 4 N towards right

A current is flowing through the loop as shown in figure below The magnetic field at centre Ois R 7 i 16R 5 16R 1 90 7 downward 15R I 2R downward downward 7 i 15R upward

A metal rod having a mass per unit length a carries a current I The rod hangs from two wires in a uniform vertical magnetic field as shown in the figure The wires make an angle with the vertical when in equilibriu Determine the magnitude of the magnetic field 150 18 100