Magnetic Field due to current Questions and Answers

47 A 4 A current carrying loop consists of three identical quarter circles of radius 5 cm lying in the positive quadrants of the x y y z and z x planes with their centres at the origin joined together value of B at the origin is a H T 10 c Ho j k T b Ho j k T 10 A d 10 i j k T

The magnetic field B in figure a and b at the point O is R D R B a A zero in both a and b C only zero in a but not equal to zero in b D none of these b B only zero in b but not equal to zero in a

A conductor carrying current 60A is in the form of a semicircle AB of radius R and lying in xy plane with its centre O at origin as shown in the figure The magnitude of B dl for the circle x z 3R in xz plane due to current in curved part AB is n Find the value of n N B A X

A perfectly conducting straight rigid rod of mass m and length L is suspended symmetrically from two identical perfectly conducting springs as shown in the figure The springs stretch a distance of xo due to the weight of the wire The circuit has a total resistance of R When the magnetic field perpendicular to the plane of the paper is switched on springs are observed to extend further by the same distance The magnetic field strength is A B C mgR EL paper mgR 2EX0 paper mgR EL map ww R K directed outward from the plane of the directed outward from the plane of the directed into the plane of the paper

An electron moves through a uniform magnetic field given by B Bi 4 71 Bx At a particular instant the electron has velocity 2 601 4 771 m s and the magnetic force acting on it is 7 99 x 10 19 N Find Bx Number the tolerance is 200 Units

4 The magnetic force acting between the side of cube is zero Magnetic field at point O due to given current carrying coil is 1 3 2R Hol 4R R 120 O 2 A Mol 1 2 R3 4 Moll 3R 1 3 2 3 2 O

The drawing shows a wire composed of three segments AB BC and CD There is a current of 1 9 A in the wire There is also a magnetic field magnitude 0 29 T that is the same everywhere and points in the direction of 2 axis The lengths of the wire segments are LAB 1 2 m Loc 0 5 m and Lco 0 5 m Find the magnitude of the force that acts on each segment B

21 A circular ring of radius 1m is placed in a dB varying magnetic field 2T s The potentia dt difference between P and Q is where ZPOQ 90 P 1 2 3 2 volt 2 1 1 volt X X ubnoo idpis X X X X X volt O for obiex 25 volt X X Q Inent 2T S OFF dt

t 7 Figure 4 128 shows a wire AB of mass m rough inclined plane of inclination a and static friction coefficient u The wire carries a current I Find the minimum magnitude of magnetic induction required to slide the wire up the inclined plane if direction of magnetic induction is normal to plane as shown in figure mg sin a ucos a A a Figure 4 128 B B

Physics C JEE Advanced A uniform magnetic field of 1 5 T exists in a cylindrical region of radius 10 0 cm it s direction being parallel to the axis along east to west A current carrying wire in north south direction passes through this region The wire intersects the axis and experience a force of 1 2 N downward as shown in figure If the wire is turned from North South to north east south west direction then magnitude and direction of force is A 12 N upward F B S W N B 12 5 downward G 1 2 N downward D 1 2 N downward

2 A cylindrical conductor of radius a has a hole of radius b bored parallel to and centred a distance d from the cylinder axis d b a The current density is uniform throughout the remaining metal of the cylinder and is parallel to the axis Find the magnitude and the direction of the magnetic field in the hole 8

75 A long straight wire along the Z axis carries a current I in the negative z direction The magnetic vector field B at a point having coordinates x y i the z 0 plane is a l y x 2 x y c Hol x y 2 x y Xavilizog b Mol xi yj 2 x y xi y 2 x y oil me d

The figure shows a closed loop bent in the form of a semi circle One bead having charge q slides from A to B along the diameter in uniform motion and other bead having the same charge slides along the arc from A to B in uniform circular motion Both take some time to travel from A to B When both the beads are at the mid point of their journey then the forces exerted by lower bead and upper bead are respectively Aro a gravitational and magnetic b magnetic and electric c electric and gravitational B

When a plate of magnetic material of size 10 cm x 0 5 cm 0 2 length breadth and thickness respectively is located magnetizing field of 0 5 10 Am then magnetic moment 5 Am is induced in it Find out magnetic induction in the plate

A magnet is made to oscillate with a particular frequency through a coil as shown in figure The time variation of magnitude of emf generated across the coil during half cycle is S e4 N vooooo v 1 m a TMSIA e wwwwww 2 104 0 e4 h e

Magnetic field at point P due to finite length wire in C G S units B 71 50a 51 136a 171 13a 171 5a 12 cm 90 Amp 12a 5 cm Ka cm Maximum

electric 54 Two equal currents are flowing perpendicular to each other as shown in the figure AB and CD are perpendicular to each and other C B D symmetrically placed with respect to the currents Where do we expect the resultant magnetic field to be zero a On CD c On both OD and BO d On both AB and CD b On AB 1996

A thin insulated wire forms a plane spiral of N 100 tight turns carrying a current I 8 mA The radii of inside and outside turns see adjacent figure are equal to a 50 mm and b 100 mm Find a the magnetic induction at the centre of the spiral b the magnetic moment of the spiral with a given current

5 54 A current flows through a rectangular conductor in the presence of uniform magnetic field B pointing out in Z direction as shown in figure 5 275 The potential difference Vp Vois equal to A Bvb Bvc B Figure 5 275 B Bvb D Bvc 2 P i

11 A paramagnetic substance in the form of a cube with sides 1 cm has a magnetic dipole moment of 20 x 10 J T when a magnetic intensity of 60 103 A m is applied Its magnetic 11 Jan 2019 Evening B 3 3 10 2 D 4 3 10 2 susceptibility is A 2 3 10 2 C 3 3 104

A coil of wire having finite inductance and resistance has a conducting ring placed coaxially within it The coil is connected to a battery at time t 0 so that a time dependent current t starts flowing through the coil If 2 t is the current induced in the ring and B t is the magnetic field at the axis of the coil due to t then as a function of time t 0 the product 2 t B t 1 Increases with time 2 Decreases with time 3 Does not vary with time 4 Passes through a maximum 1 2 3 4

Iwo ends of an inductor of inductance L are connected to two parallel conducting wires A rod of length and mass m is given velocity v as shown in figure 5 283 The whole system is placed in perpendicular magnetic field B Find the maximum current in the inductor Neglect gravity and friction anywhere mvo L mv oooooooooooo Figure 5 283 BY m I Vo OB D None of these

A vertical wire carries a current of 6 0A What is the Magnetic field at a 20 mm and b 40 mm from the wire 4 An electron moving at 2 0x10 ms passes at 90 through a magnetic field of flux density 2 5x10 oil l

In the operating room anesthesiologists use mass spectrometers to monitor the respiratory gases of patients undergoing surgery One gas that is often monitored is the anesthetic isoflurane molecular mass 3 06 x 10 25 kg In a spectrometer a single ionized molecule of isoflurane charge e moves at a speed of 7 93 x 103 m s on a circular path that has a radius of 0 130 m What is the magnitude of the magnetic field that the spectrometer uses Number i Units

42 An infinitely long current carrying wire and a small current carrying loop are in the plane of the paper as shown The radius of the loop is a and distance of its centre from the wire is d d a If the loop applies a force F on the wire then 19 Jan 2019 Morning A Fo a d C 5 Fx 2 d B Fx 4 D F 0

4 28 Two identical wires each of length L are bent to form a circular loop and a square loop If the same current i flows in the two wires then the ratio of the magnetic inductions at the centre of the circular and square loops is A 2 2 B T 4 2 C 8 2 D 1

place Two similar magnets of magnetic moments M and M are taken and vibrated in a vibration magnetometer with their a Unlike poles together b Like poles together respectively The ratio of their time period is 2 1 Then the ratio M M is 1 0 8 3 2 2 0 6 4 1 67

A metal sheet placed in magnetic field which changes from zero to maximum If figure showns direction of eddy currents then direction of magnetic field is W N S E 1 Perpendicular to the plane of the paper inwards 2 Perpendicular to the plane of the paper outwards 3 From West to East

nducting wire ABC has a mass of 10 g A current of 2 A flows through it The wire is kept in a uniform magnetic field B 2 T The acceleration of the wire will be B X 4 cmA X X X x A x 1 Zero 2 12 ms 2 3 1 2 x 10 3 ms X 5 cm X C

A hollow tube is carrying an electric current along the length distributed uniformly over its surface The magnetic field O O O O increases linearly from the axis to the surface is non zero inside the tube inside the tube is zero is zero just outside the tube

The current density Jinside a long solid cylindrical wire of radius a 5 30 mm varies with radial distance r from centre the according to J Jor2 a where Jo 220A m Find the magnitude of the magnetic field at a r a 2 b r 2a Hint In a culinder dA 2rrdr

long straight wire carries a current TU i in A 2 sin oot sin cut 3 maximum value of magnetic field produced by the 7 wire at a distance m is ASV 10 1 2UT 4 cos wt The 2 4uT epai

4 14 The configuration of some current carrying wires is shown in figure 4 217 All straight wires are very long Both AB and CD are arcs of the same circle both subtending right angles at the centre O The magnetic field at O is A C Hoi 4 R Hoi 2 R B B R D Figure 4 217 B D Hoi 2 4TR Moi 2 R C 1

Which of the following is not true in case of motion of a charged particle which is proje perpendicularly in a magnetic field 1 its kinetic energy remains constant 3 Its speed remains constant 2 Its momentum remains constant 4 Its velocity will change

A small conducting rod of length moves with a uniform velocity XXXXXB v in a uniform magnetic field B XX xx as shown in figure A The end X of the rod becomes xxxxxxx positively charged X B The end Y of the rod becomes positively charged X

a particle 2 An electron is projected horizontally with a kinetic energy of 10 keV A magnetic field of strength 1 0 10 7 T exists in the vertically upward direction a Will the electron deflect towards right or towards left of its motion b Calculate the sideways deflection of the electron in travelling through 1 m Make appropriate approximations

3x y Find the force Question 15 A wire having current 3A is lying is x y plane along curve in Newton acting on wire due to uniform magnetic field of magnitude B 1 T and at an angle 30 with x axis A 1 3 B 30

Two straight infinitely long wires are fixed in space so that the current in the 2 left wire is 2 A and directed out of the plane of the page and the current in the right wire is 3 A and directed into the plane of the page In which region s is are there a point on the x axis at which the magnetic field is equal to zero due to these currents carrying wires Justify your answer Region I 2A Region II 3A Region III

Q 4 Long thin wires 1 2 and 3 are all parallel to the z axis Wire 1 carries current I into the xy plane and crosses the xy plane at d 0 0 Wire 2 carries current out of the xy plane and crosses the xy plane at 0 0 0 Wire 3 carries current I out of the xy plane and crosses the xy plane at x 0 0 with x positive Now x is such that the force per unit length on wire 3 along the positive x direction is maximised What is the value of this maximum force per unit length on wire 3 Max score 1 Neg score 0 HoII1 4nd Mo II1 2nd MOII 8nd MOII

A wire carrying a 30 0 A current passes between the poles of a strong magnet that is perpendicular to its field and experiences a 2 16 N force on the 6 00 cm of wire in the field What is the average field strength in Tesla

Q 5 A long cylindrical conductor carries a current of 2 Amperes Its radius is 2 cm The magnitude of the magnetic field on the surface of the conductor is B x 10 3 T What is the closest value of B Max score 1 Neg score 0 3 4 8 5 5 1 17

Electromagnetic induction 18 1 mark B T wire A wire is moved through a magnetic field sweeping an area of 0 140 m in a time of 67 0 milliseconds This causes a current of 60 0 mA to be induced through the wire which is part of a circuit with a resistance of 480 Calculate the magnetic flux density in tesla X motion

A solenoid 4cm in diameter and 20cm in length has 250 turns and carries a current of 15A Calculate the flux through the surface of a disc of 10cm radius that is positioned perpendicular to and centered on the axis of the solenoid

A coil 2 0 cm in diameter has 300 turns If the coil carries a current of 10 mA and lies in a magnetic field 5 x 10 2 T the maximum torque experienced by the coil is A 4 7 x 10 2 N m Olympiad State 1 2017 D 4 7 x 10 8 N m B 4 7 x 104 N m 53 PIA Near City Mall Jhalawar Road Kota Raj 324005 C 4 7 x 10 5 N m

4 17 The radius of a coil of wire with N turns is 0 22m and 3 5A current flows clockwise in the coil as shown A long straight wire carrying a current 54A toward the left is located 0 05 m from the edge of the coil The magnetic field at the centre of the coil is zero tesla The number of turns Nin the coil are A 4 C 7 97 Figure 4 219 B 6 D 8

6 A wire is bent into a rectangular loop of width 2L and height L as shown in Figure If L 10 centimeters and the wire carries a current 15 Amps L 2L a 6 points Find the magnetic field at the center of the rectangle magnitude and direction

5 The magnetic field dB due to a small current element dl at a distance r and element carrying current i is a dB Ho 4 Vector form of Biot savart s law is i c dB 0 2 dl xr r or dl xr 2 CBSE PMT 1996 MP PMT 2000 MP PET 2002 13 WB JEE 2009 KCET 2018 b dB Mo 2 4T dl xr r d dB dl xr 4

A cylindrical bar magnet is rotated about its axis Figure given alongside A wire is connected from the axis and is made to touch the cylindrical surface through a contact Then NCERT Exemplar a a direct current flows in the ammeter A b no current flows through the ammeter A bar c an alternating sinusoidal current flows through the ammeter A with a magnet time period T 2 0 d a time varying non sinusoidal current flows through the ammeter A axis N B

Ho where xis the distance from the dipole If we replace pm and 1 in the above expression we obtain the result for B for a point in the plane of the loop at a distance x from the centre For x R B Ho m 4 x 3 X R 14 31b 11 ad 14 31bll become exact for a

Q 24 A circular coil of one turn is formed by a 6 28m length wire The magnetic field at the centre of coil is 2 T Then current in Coil 1 41 A 6 28 A 3 14 A Incorrect 1 01 45 2 14 A