Magnetic Field due to current Questions and Answers

Q 2 A fixed long thin wire carrying current I lies along the x axis A fixed square loop of side length a is placed on the xy plane so that two of its sides are parallel to the x axis and the other two are parallel to the y axis The side parallel to and closest to the wire is at a distances from the wire The loop also carries a current I in the clockwise direction What is the total force on the loop due the wire Max score 1 Neg score 0 2 1 a Ts a s MoI a 2 s a s HoI a Ts a s HoI q a 4 s a s

a Magnetic field at axial point which is well inside the solenoid Honl 2 b Magnetic field at both axial end points of solenoid 0 0 and 9 180 B 0 90 and 02 180 B Honl 2 cos 0 cos 1807 Honl 2 cos 90 cos 1801 Honl 2 0

A constant force F is being applied on a rod of length kept at rest on two parallel conducting rails connected at ends by resistance R in uniform magnetic field B as shown the power delivered by force will be constant with time 2 the power delivered by force will be increasing first and then will decrease 3 the rate of power delivered by the external force will be increasing continuously 4 the rate of power delivered by external force will be decreasing continuously Gal aft side of line PO has a magni

A B ring along the axis of the ring and it passes through the ring N S B A are right left faces respectively 1 when magnet goes towards the ring the face B becomes south pole and the face A becomes north pole 2 when magnet goes away from the ring the face B becomes north pole and the face A becomes south pole 3 when magnet goes away from the ring the face A becomes north pole and the face B becomes south pole 4 the face A will always be a north pole tic particle is released from a point on the axis

uniform magnetic field of intensity directed into the plane of the paper exists in the cylindrical region of radius 1 m A uniform loop of resistance 100 olded in the form of equilateral triangle of side length 2m is placed as shown in figure Find the maximum potential drop in volt in wire AB A xx1m xxx x X x xx X xxx B sin 2t B

3 In L C oscillation maximum charge on capacitor is Qo The current in the circuit when 50 energy is electrical and 50 magnetic is 1 Qo LC 9 C L 2 LC

m 4 A charged particle moving with some unknow velocity enters into an unknown uniform magneti field The kinetic energy of the particle 1 Increases 2 Decreases m 3 Remains constant 4 Depends on the value of intensity of field in proiecto

1 direction shown are placed concentrically in the e conducting rings each having current in the same plane as shown in the figure The radii of rings are R 2R 4R 8R 00 Net magnetic field at the common centre O of rings will be 8 Ho R 2 Hol 2R 1 Ho sine 4nd 4pol nd si 14 3 Two gec magneti their id oscilla taken the F the ma 1 15

Define losses of transformer The efficiency of 400KVA singe phase transformer is 98 77 when delivering full load at 0 8 pf lagging and 99 13 at half full load at unity pf calculate 1 Iron loss 2 Copper loss

3 CW In horizontal plane A current is flowing in electricity line towards north the direction of magnetic field at a point which is just 4 CW In vertical plane below the line 1 towards north K 2 towards south 4 towards west the direction of magnetic field of a point which 3 towards east

In the circuit shown X is joined to Y for a long time and then x is joined to Z The total heat produced in R is XH 1 2 3 4 LE 2R LE 2R22 LE 2R R2 LE R 2R R 00000 L E X Z www R

An irregular closed loop carrying a current has a shape such that the entire loop cannot lie in a single plane If this is placed in a uniform magnetic field the force acting on the loop 1 must be zero 2 can never be zero 3 may be zero 4 will be zero only for one particular direction of the magnetic field

pop The magnetic field intensity at the point O of a loop with current i whose shape is illustrated below is b 16 3 1 4T 2a Hoi 3 2 Hoi 1 2m a h a b 2 4 Moi 2 4 a 2 0 Moi 1 1 4 a b

A charged particle is projected in air horizontally near the earth s surface at a point where horizontal component of magnetic field s absent Considering the effect of vertical omponent of the earth s magnetic field and the gravitational field due to the earth the path of the particle will be 1 circular 3 straight line 2 helical 4 parabolic

Consider a cube of side a 0 1 m placed such that its six faces are given by equations x 0 x a y 0 y a z 0 and z a placed in electric field given by E x i yi N C Find the electric flux crossing out of the cube in the form of px 10 4 N m C and fill value of p in OMR Sheet

4 Move towards ve x axis a current PQ is part of a very long wire carrying a current and passing close to the circular coil If the direction of the current are those as shown what is the direction of force acting on PQ 1 Parallel to PQ towards P At right angles to PQ to the right P O 2 Parallel to PQ towards Q 4 At right angles to PQ to the left

In a cyclotron a charged particle 1 undergoes acceleration all the time 2 speeds up between the dees because of the magnetic field 3 speeds up in a dee 4 slows down within a dee and speeds up between dees 9 fan til E 1 2 3 4 HE

A long straight hollow conducting tube carrying a current along ve y axis as shown in the figure The line PQ is parallel to positive y axis The magnetic field at 1 2 3 and 4 is B B2 B3 and B4 respectively Then R R 2 R 4 42 3

Consider two coils of radii r and r placed at a distance d away as shown in the figure Assuming the length of the coils 1 1 d with n n the 1 2 number of turns per unit length of the two coils respectively the mutual inductance of the two coils is 4 00000 00000

X X X X X X X X X X X RX X X X X X X X X X X X X X X X X X Vo If this rod length 1 is released wit velocity V then 0 1 It will continue to move with constant 2 It will accelerate 3 It will stop after sufficiently long tim 4 None of these dana in ostabli

Equation sin cot implies that the 12 dt equation for i t the current as a function of time must be such that di 1 its slope is a sinusoidally varying quantity dt with the same phase as the source voltage 2 an amplitude given by 3 Both 1 and 2 4 Neither 1 nor 2

lonized hydrogen atoms and a particles with same momenta enters perpendicular to constant magnetic field B The ratio of thei radii of their paths will be 1 2 1 3 4 2 1 2 4 1 4

30 A U shaped wire having current i is place of magnetic field as shown in figure the magnetic force acting on wire is 41 1 r 21 Bi 3 2Bir Exi 2 r 21 Bi 4 2Bil Road Office

a starts 24 A particle of specific charge charge mass moving from the origin under the action of an electric field E Eoi and magnetic field B Bok Its velocity at x0 0 0 is 41 31 The value of xo is 25 2 Eo a 13 Eo e 2 Bo b 16 a Bo E d 5a 2 Bo

long straight solid metal wife of radius 2 mm carries a current uniformly distributed over its circular cross section The magnetic field induction at a distance 2 mm from its axis is B Then the magnetic field induction at distance 3 mm from axis will be Options 2B 3 B 2

xo A straight rod of mass m and length L is suspended from the identical springs as shown in figure The spring is stretched a distance due to the weight of the wire The circuit has total resistance R When the magnetic field perpendicular to the plane of paper is switched on springs are observed to extend further by the same distance The magnetic field strength is f 100 www E F ee

A ring of radius 5 m is lying in the x y plane and is carrying current of 1 A in anti clockwise sense If a uniform magnetic field B 41 3 is switched on then the co ordinate of point about which the loop will lift up is A 5m

A wire of length is formed into a circular loop of one turn only and is suspended in a magnetic field B When a current I is passed through the loop the torque experienced by it is A 1 4n BIC B 1 4 IB C 1 4n B IC D 1 4 BI E 1 4m B I

In the given figure all surfaces are smooth The system is released from rest Find the value of m in kg for which 1kg block does not slide on wedge 30 YOUR ANSWER 2 kg ATT 9

A conductor moves with a velocity 12m s at an angle of 90 to a magnetic field produced between two square faced poles of side length 2cm If the flux leaving the pole face is 5 Wb find the magnitude of induced emf in each case

45 15 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 Weber 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 2015 Pre a 0 12 Nm b 0 15 Nm c 0 20 Nm d 0 24 Nm 16 Two identical long conducting wires AOB and COD are placed at righ

Three long wires are placed along X axis Y axis and Z axis and they carry equal current in positive direction The magnetic field produced due to them at point a a 0 has magnitude 2 1 3 Ho 2 a 3 ol Am 4 Ho 4 2 a Ho

An infinitely long wire carrying a current I in vertically upward direction y direction is placed near the surface of earth as shown in figure Neglect the earth s magnetic filed Y A O a 0 At some time t a particle is at point A a 0 and moving towards origin with velocity V If the acceleration of particle at point A is 2g in downward direction then B X particle is negatively charged particle is positively charged YOU MARKED

can even be used analytically such as in a mass spectrometer Q 4 A neutron a proton an electron and an a particle enter in a region of uniform magnetic field with equal velocities The magnetic field is perpendicular and directed into the paper The tracks of the particles are shown in figure The electron will follow the track 1 Point A B U D 5

2 Points 10 3 N 2 5 x 10 3 N 0 Three long straight parallel wires carrying current are arranged as shown in the figure The force experienced by a 25 cm length of wire C is 1 5 x 10 3 N 30 A 3 cm 2 cm 10 A 20 A

35 A straight thin conductor is bent as shown It carriers a current of i ampere The radius of curvature of the circular arc is r meter The magnetic induction at the centre of semicircular arc Ho 4 r KING CH 0 2 infinity Hoi 4 4 T

Detailed mai samajha dijiye sir A cell is connected between the points A and C of a circular conductor ABCD of same material with centre at O If B and B are the magnitude of magnetic field at O due to current in ABC and ADC respectively then ratio is B B 05 02 1 B 60

If the streams of protons closely move parallel to each other in the same direction then they 1 do not exert any force on one another 2 repel each other 3 attract each other 4 get rotated to be perpendicular to each other E

A straight conductor of length is wound in to a circular coil of n turns For a current i flowing through the coil the magnetic induction at the centre is B When the coil is now wound to 2 n turns magnetic induction at the centre will be A 4 B C 2 B B 3 B D B

2 Coefficient of volumetric expansion a is not a constant It depends on temperature Variation of a with temperature for metal is pa K T 1 a 2 1 T Bu a f 1 161 1 19 T 2 C ufte

Z A conductor lies along the z axis in the linear region defined by 1 5 m z 1 5 m It carries a fixed current of 10 A in the 2 direction Refer the figure shown below Note that B 3 0x 10 4e 0 2x T Find the power required to move the conductor at a constant speed to x 2 m y 0 m in 5x 10 3 s Assume the motion of the conductor to be parallel along the x axis y 2 0 1 5 NA 1 B 1 5

Zero Marks 0 In all other cases One coil of resistance 400 is connected to a galvanometer of 1600 resistance The coil has radius 6 mm and turns 100 This coil is placed between the poles of a magnet such that magnetic field is perpendicular te coil If coil is dragged out then the charge through the galvanometer is 32 C Find magnetic field in Tesla

Across a long conductor 2A current is flowering At 10cm from it another 5cm long conductor carries 3A The values of B at short conductor and force on it in the multiple of 10 6 are 1 4T 6N 2 4T 0 6N 3 6N 0 4T 4 6N 6T

Current through an inductor is increasing according to 2t du Variation of rate of increment of its energy with time f is correctly shown in the graph Only one correct answer B O 2 36 du dt K du dt 12

A metallic rod AB moves on a V shaped conducting wire with speed v as shown in figure such that at given instant of time OA OB L If magnetic field in the space is perpendicular downwards and has magnitude B then induced emf in the rod is B 60 OBVL O 3 BVL Bvl 2 O Zero

Two circular coils have their centres at the same point The mutual inductance between them will be maximum when their axis is O At 45 to each other At 60 to each other O Parallel to each other O Perpendicular to each other

Charges and Magnetism 105 Two parallel beams of electrons are produced parallel to y axis such that speeds of electrons is v If speed of light is c then ratio of electric force to the magnetic force between electron beams is 1 3 12 01 2 4 las

XM Two circular coils X and Y have equal number of turns and carry equal currents in the same sence and subtend same solid angle at point O If the smaller coil X is midway between 0 and Y then if we represent the magnetic induction due to bigger coil Y at O as By and that due to smaller coil X at O as Bx then Y 1 3 By Bx By Bx 1 d X 2 4 BY Bx By Bx 2 4 ALLEN O 38

A small magnetic dipole is kept at the origin in the x y plane A long wire L is located at z a in the x z plane with a current flowing in the positive x direction Another long wire L is at z a in y z plane with the same current I as in L flowing in the positive y direction The angle 8 made by the magnetic dipole with the positive x axis is 225 120 45 270

Example 22 Current is flowing in a wire frame kept as shown in the figure where EDCF is in y z plane and AFC is in x z plane Current in the wire frame is i and length of each side is a Find the magnetic mome Imon J plez plution as you Above wire frame can be seen as composed of two rectangular wire frames where current CF of loop EDCF cancels current FC in AFCB Magnetic moment M M M J Mis magnetic moment of AFCB C M ia j M2 is magnetic moment of FEDC M ia i So M ia i i Z E 9 GEZ A B Imp The electron of charge e perform constitutes a current I in the loop The current in the loop The magnetic moment u ass 1 According to Bohr s model Imp 1 T Here L is the angular inom 20 Vectorially Tim