Magnetic Field due to current Questions and Answers

48 Application junction of a forward bias to a p n CBSE AIPMT 2005 a increases the number of donors on the n side b increases the electric field in the depletion zone c increases the potential difference across the depletion zone d widens the depletion zone the following If donors get accumulated on n Side then the majority charge aveiers which are also e dono will not undergo repritsion as in n side donors are e s only

A charged particle q m enters into a cylindrical region of radius R with velocity Vo In cylindrical region uniform magnetic field B is present If R Vo then qB magnitude of change in velocity of particle as it emerges out of the magnetic field is given by AVV Find value of 1 Vo 9 m R Xx

17 The velocity of two alpha particles A and B in a uniform magnetic field is in the ratio 1 3 They move in different circular orbits in the magnetic field The ratio of the radius of curvature of the two paths is a 1 3 b 3 1

18 A long wire carries a steady current It is bent into circle of one turn and the magnetic field at the center of the coil is B It is then bent into a circular coil of n turns The magnetic field at the center of the coil will be a nB c 2nB b n B d 2n B

5 51 A long straight wire carries a current I 10 sin cot 8 and lies in the plane of a rectangular loop of N turns of wire as shown in figure 5 351 The quantities o w and 8 are all constants Determine the EMF induced in the loop by the magnetic field due to the current in the straight wire Assume I 50A w 200 s N 100 a b 5cm cm and 20cm I Ho Nolo a b 200 N turns b Figure 5 351

conducting rod is moving under the influence of a constant force between two parallel ideal conducting rails There is a capacitor connected between the ends of the two rails A uniform magnetic field exists perpendicular to the plane of the rails Neglecting all kinds of dissipative forces and gravity identify the correct statement X X X F constant X X X 4 1 the velocity of the rod becomes constant after a certain duration 2 the acceleration of the rod becomes zero after certain instant 3 the acceleration of the rod becomes constant immediately after the start of motion

0 5 3 The effective radius of a circular coil is R an number of turns is N The current through it is ampere The work done in rotating the coil b angle of 180 in an external magnetic field B wi be initially plane of coil is perpendicular to magnetic field 1 NiR B 3 2NiB 2 2NiR B 4 Zero

A 0000000 0000lllllll B If the maximum and minimum equivalent inductance of the combination is found to be 16H and 3H the coupling constant is 1 00000000000 0000000 12 13 2 13 12

5 30 A thin non conducting ring of mass m radius a and uniformly distributed charge q is place inside a solenoid magnetic field with its plane normal to B and coaxially with solenoid as shown If B is changing with time as B kt find the angular speed attained by ring after time t qkt Ans 2m F X X E X X X X X X X X X X X X Figure 5 339 F X X Solenoid ST C C

A sliding conducting bar of mass m resistance R is released from rest It starts sliding due to the current drawn from a battery of emf in a steady inward magnetic field Find the variation of its speed with time Also find the terminal speed of the bar D 00 E R

n the ar to 5 48 A straight conducting rod PQ is executing SHM in xy plane from x dtox d Its mean position is x 0 and its length is along y axis There exists a uniform magnetic field B from x d to x 0 pointing inward normal to the paper and from x 0 to d there exists another uniform magnetic field of same magnitude B but pointing outward normal to the plane of the paper At the instant t 0 the rod is at x 0 and moving to the right The variation of induced EMF across the rod PQ with time is best represented as A C MA ms YA X X X P X X X X d X X X X X X X 9 Figure 5 271 D d AMA EA AA

Figure shows a square loop 10 cm on each side in the x y plane with its centre at the origin An infinite wire is at z 12 cm above y axis i 65A 10 cm B Z i 78A 12 cm C y What is torque on loop due to magnetic force If torque is expressed as x X10 7 N m fill value of x

as Electrical resistance of certain materials known superconductors changes abruptly from a non zero value to zero as their temperature is lowered below a critical of An interesting property temperature Tc 0 superconductors is that their critical temperature becomes smaller than Tc 0 if they are placed in a magnetic field i e the critical temperature Te B is a function of the magnetic field strength B The dependence of Te B on B is shown in 2010 the figure a c Tc B A 6 In the graphs below the resistance R of a superconductor is shown as a function of its temperature T for two different magnetic fields B solid line and B dashed line If B is larger than B which of the following graphs shows the correct variation of R with T in these fields R B21 Tc 0 B B b d R B2 B B B2

3 A proton moving along the x axis enters a magnetic field If the proton experience a magnetic deflection in the y direction then the magnetic field must have a compones A along the axis B along the a axis C along the y axis D along the y axis

A conducting rod AB of lemgth 2 I moves through a uniform magnetic field B The rod makes an angle with the vertical while it falls with a uniform linear velocity v The potential difference between the two ends of the rod is Bv 1 B

Two infinite wires carrying current lo and 2 are separated by distance d Magnitude of magnetic field at a point Pat a distance d from both the wires is O O 9 0 0 4x d vunh d 21

A square loop of area 2 5x10m and having 100 turns with a total resistance 10092 is moved out of uniform magnetic field of 0 4 T in 1 sec with a constant speed Then the work done in pulling the loop is 1 0 3 1 J 2 1mJ 4 0 1 mJ

In figure ABCDE is a channel in the vertical plane part BCDE being circular with radius r A ball is released from A and slides without friction and without rolling Show that it will complete the loop path ifh is greater than 5r 2 h E

Two concentric circular loops of radii cm and 14 cm are place in the Y Z plane as shown in the figure The magnetic moment of this loop system is Z 55 x 10 3 Am 55 x 10 3 Am O 33 x 10 Am 33 10 3 Am 10 A 5A

A charge particle q m is projected from origin at t O with velocity vo making an angle of 37 with x axis in x y plane A uniform magnetic field Boi exists in the region Find the distance of the particle from origin at t 37 4mvo 9 5qBo 9 3mvo 5qBo Vo 2mvo END 7 9 70 mvo 2 4 qBo 472 9 X TUM qBo

A charge particle q m is projected with velocity vo in uniform magnetic field region of width d Strength of magnetic field region is Bo Value of dis given in Column 1 Time spent by the particle and average force acting on the particle in field region till it exits the field is given in Column II Match the entries X X X X X X X X X X X x X X X Column 1 xx 02 d X X 91 d J2mv 9B X X 03 d mvo 2q8 04 3mvo 2060 amy CE XXX XX 2 Column Il A1 A2 AB A4 A5 m 2g B FO qB 6qB 20080 m 3q B

Two infinite wires carrying current Io and 210 are separated by distance d Magnitude of magnetic field at a point P at a distance d from both the wires is O O 9 0 0 4nd 5 olo nd olo d 2

X It is rotated about y axis with angular velocity w as shown l 2 A B is proportional to A f magnetic field at point O due to rod segment AB is B then B is proportional to X B B is proportional to w Read Less

Two infinite wires carrying current and 2 are separated by distance d Magnitude of magnetic field at a point P at a distance from both the wires is O 24 guolo 4nd

4 32 2 A conducting ring is placed around the core of an electromangnet as shown in fig When key K is pressed the ring Ring U 1 Remain stationary 2 Is attracted towards the electromagnet 3 Jumps out of the core 4 None of the above

A long straight hollow conductor tube carrying a current has two sections A and C of unequal cross section joined by a conical section B 1 2 and 3 are the points on a line parallel to the axis of the conductor The magnetic fields at 1 2 and 3 have magnitude B B and B3 A B 1 B B B3 3 B B B3 2 3 2 B B B3 4 B B B3

The SI unit of Magnetic Field is Tesla and the C G S unit is Gauss Which of the following is the correct relation A 1 Gauss 104 Tesla B 1 Tesla 104 Gauss c 1 Gauss 0 01 Tesla

charge particle q m is projected with velocity vo from origin in a region where magnetic field 56 Box K where is constant If maximum x coordinate of particle is x and vis speed t that point then B Ov Vb OV X O Xm 2mvo gBo mul 60

L Four long current carrying wires each having current are placed along z axis at point P Q R and Co ordinates of these points are shown in figure If line integral B d along the line x a from pc A a a to B a a is Nul then value of N is a a 22 SO OP aa 22

A solehold of length 10 cm and radius 1 cm contains 200 turns and carries a current of 10 A The value of pole strength of each pole is 1 2 Am 2 2 Am 4 10 Am 3 4 Am

triangle ABC current flows in anticlockwise sense Magnetic field at point A and B is B and B respectively Value of 37 PP in

charged with linear charge density It is rotated about y axis with angular velocity w as shown y O 2 A Read Less If magnetic field at point O due to rod segment AB is B then B is proportional to A B Ris proportional to 2

quare loop carrying current is placed in the plane of long wire carrying current as shown Magnetic force on the loop is L Hello 21 Holly Hollo t

A thin uniform rod OB of length is uniformly charged with linear charge density A It is rotated about y axis with angular velocity was shown O l 2 A B Read Less If the axis of rotation is changed to axis passing through A and parallel to y axis then Magnetic dipole moment becomes Q 0 24 Magnetic dipole moment becomes Q 12 Magnetic dipole moment becomes Q 6 Magnetic dipole moment becomes Q 3

charge particle q m enters magnetic field region of width d as shown Magnetic field inside the region is uniform and equal to Bo If d mothen distance travelled by the particle bef 2q8 exits the field region is Vo X X

A beam of cathode rays is subjected to crossed Electric E and Magnetic fields B The fields are adjusted such that the beam is not deflected The specific charge of the cathode rays is given by 1 3 E 2VB 2VB E 2 4 lom B 2VE 2VE B difference between

Two point charge A and B have charge 0 5 C and 2C respectively and their position vectors are 1 j k and 1 j 3k respectively The force on the charge at A due to B is Ok i j K N 12 3 O O k 24 3 1 1 k k 24 3 i j k k 24 3 1 1 k

A particle is moving in a uniform magnetic field Which of the following conditions will lead to a non zero force on the particle A The particle has no charge B The particle has charge and the velocity of the particle is parallel to the direction of the magnetic field C The particle has charge and the velocity of the particle is opposite to the direction of the magnetic field D The particle has charge and the velocity of the particle is perpendicular to the direction of the magnetic field

4 13 A charged particle of specific charge charge mass o is released from origin at time t 0 with a velocity given as v v i j The magnetic field in region is uniform with magnetic induction B Boi Coordinates of the particle at time t TC Boa A vo 2Boa aBo Boa 211 2v0 vo B Vo 2B a 3 0 0 are

A solenoid having 200 turns of length 2m carries a current of 5 A The radius of the solenoid is 0 75 m The magnetic field at a point 1m from one end of the axis of the solenoid in T is 1 120 T 3 160 2 60 4 320

Two infinite wires carrying current lo and 2 0 are separated by distance d Magnitude of magnetic fiel at a point P at a distance d from both the wires is O 1 O O 9 0 0 4nd 5 olo nd O olo nd d 2

10 Find the magnitude and direction of a force vector acting on a unit length of a thin wire carrying a current 8 04 at a point O if the wire is bent as shown in a Figure a with curvature radius R 10 cm b Figure b the distance between the long parallel segments of the wire being equal to 1 20 cm R a 0 b L

Di Iwo conducting rails are connected to a source of emf and form an incline as shown in figure A bar of mass 50 g slides without friction down the incline through a vertical magnetic field B If the length of the bar is 50 cm and a current of 2 5 A is provided by battery Value of B for which the bar slide at a constant velocity X10 Tesla 8 10 m s 0 0 37 B E Q

26 When a bar magnet falls through along a infinite long metal cylinder fixed with its axis vertical The final acceleration of the magnet is A equal to g C greater than g but finite B less than g but finite D equal to zero

rod A rod B In the given figure force on rod A and rod B are in direction respectively 1 Rightward direction Leftward direction 3 Leftward direction Leftward direction 2 Rightward direction Rightward direct 4 Leftward direction Rightward directio

32 A magnetic field may 1 Change the velocity of a charged particle 3 Change the K E of a charged particle 2 Change the speed of a charged particle 4 Stop a moving charged particle

2 A conducting circular loop is placed in a uniform magnetic field B 0 025 T with its plane perpendicular to the loop The radius of the loop is made to shrink at a constant rate of 1 mm s The induced emf when the radius is 2 cm is a 2 V b V TU c V d 2 V

D A uniform magnetic field of 1000 G is established along the positive z direction A rectangular loop of sides 10 cm and 5 cm carries a current of 12 A What is the torque on the loop as shown in the figure B

13 In the series LCR circuit as shown in the figure the voltmeter V and ammeter A readings are 400 V 400 V A a V 100 V b V 100 V c V 400 V d V 300 V V ww R 50 Q 100000 L 100 V 50 Hz I 2 A I 5 A I 2 A I 2 A C

A toroidal coil of inner radius 15cm and an outer radius 16cm carries a current of 10A in its turns The maximum field within the torus is 160G The number of turns in the torus is A 190 B 204 C 1200 D 1280