Magnetic Field Questions and Answers

This section contains 15 SINGLE CORRECT TYPE questions Out of these 15 questions A current is flowing through the sides of equilateral triangle of side a The magnitude of magnetic field at the centroid of triangle is Ho Bi 3i 2 a Mo gi 2 a Ho 6i 2 a O No 6 3 2 Read More a

A rod AB slides on V shaped wire with speed vin magnetic field B such that at an instant OA OB 1 If the induced emf in the loop OAB at this instant is given by Bvl then find the value of n 90 8 B V

dt SolveLancer Test In the given figure a ring of radius r mass m is uniformly charged and has total charge Q The ring is free to rotate in the plane Magnetic field is turned on at t 0 and changes at rate 48 A charge Q is placed at center C of the ring Find the time when tension in ring is instantaneously zero Test k SolveLancer b c km km KmQ Br 0 B

1 A dip needle in plane perpendicular to magnetic meridian excep magnetic equator will remain 1 Horizontal 2 Vertical 3 At an angle 5 with vertical 4 In any direct on

A dip circle is taken to a magnetic pole Initially it was in vertical direction If dip circle is now turned by 90 in a vertical plane the needle will 1 Stay in horizontal direction 2 Stay in vertical direction 3 Can stay in any direction it is released 4 Can stay in any direction except vertical or horizontal

Two coherent light sources each of wavelength A are separated by distance 3A The total number of minima observed on the line AB which runs from to o is P 3 Only one correct answer A 2 B 4 C 6 0 B 8

A charged particle having charge 2 C is projected with velocity 21 33 m s inside a region having E 23 N C and B acting on the particle in newtons Only one correct answer A B 30i 16j C 30i 16j D 30i 16j 5 T Find the Lorentz force G

V A m 2qB X XXX X X X X X X X 2B W X X B X XXX X B K W if v is the velocity just required for a charge particle of mass m and charge q to pass through the magnetic field Particle is projected with velocity v then how much time does such a charge spend in the magnetic field of the two magnetic fields Tm qB C 7m 4qB basga fab D 3 m 2qB

A current 1 flows along a triangular loop having sides of equal length a The strength of magnetic field at the centre of the loop is A B 3 I 2 a Your Answer 9 0I 2 Correct Answer

An electron of mass m and charge e is accelerated by a potential difference V It then enters a uniform magnetic field B applied perpendicular to its path The radius of the circular path of the electron O r 2mV eB 2meV B 2mB eV

A strong magnetic field is applied to a proton at rest Then a the particle moves in opposite direction of the applied field b the particle moves in the direction of the applied field c the particle continues to be at rest consider the proton as a charged particle only d the particle executes circular motion in magnetic field

A circular current loop of magnetic M is in an arbitrary orientation in an external magnetic field B The work done to rotate the loop by 30 about an axis perpendicular to its plane is A MB MB 2 C MB 2 B 3 D Zero

3 Current i is carried in a wire of length L If the wire is turned into an equilateral triangular coii the maximum magnitude of torque in a given magnetic field B will be il B iL B il B 9 2 3 3 2 12 3 1 il B 6 3

1 THE FORCE EXPERIENCED BY A POSITIVE CHARGE q MOVING WITH A VELOCITY V PERPENDICULAR GIVEN BY TO THE DIRECTION OF MAGNETIC FIELD B IS O qvB OqvB O Zero O 1 2qvB 1 point

STAT A cubic cell consists of two atoms of masses m and m m m with m and m atoms situated on alternate planes Assuming only nearest neighbor interactions the centre of mass of the two atoms a moves with the atoms in the optical mode and remains fixed in the acoustic mode 1 b remains fixed in the optical mode and moves with the atoms in the acoustic mode c remains fixed in both optical and acoustic modes BUR d moves with the atoms in both optical and acoustic modes

Q 1 The given figure shows an inductor and resistance fixed on a conducting wire A movable wire PQ starts moving on the fixed rails from t 0 with constant velocity 1 m s A constant magnetic field B 2T exist perpendicular to the plane of paper The work done by the external force on the wire PQ in 2 second is L 2H Answer A B 00000000 C R 20 Your Attempt 16 J 32 J 48 J B 2T 2m P v 1m s Q Correct answer Rate this quest

A charge particle having charge 2 C is thrown with velocity of 21 31 m s inside a region having 2 N C and magnetic field 5k T The Lorentz force acting on particle is 30i 16 N C 15i 20 N O 15i 30j N

gure shows a particle of charge q and mass m moving with velocity v along the x axis enters a gion of uniform magnetic field Minimum value of v so that the charge q is deflected by an angle 30

20 180 Two similar circular coaxial loops carry equal currents in the same direction If the loops are brought nearer what will happen Current will increase in each loop Current will decrease in each loop Current will remain same in each loop Current will increase in one and

4 None of the above The maximum electric field at a point on the axis of a 36 uniformly charged ring is E At how many points on the axis will the magnitude of electric field be E2 1 1 2 2 3 3 4 4 4 340 fait for an E 2 1 I fa fa 2 2 3 3 en f 4 4

Using ampere s circuital law we can find A Magnetic field due to a long isolated current carrying straight wire B Magnetic field inside a long current carrying solonoid C Magnetic field due to a current carrying circular loop at points on its ax D Magnetic field due to a finite current carrying wire

A coil having n turns and resistance R2 is connected with a galvanometer of resistance 4RG combination is moved in time t seconds from a magnetic flux weber to weber The current in the circuit is a 5 Rnt b n 6 6 SP c d n 6 6

A tangent galvanometer has a coil of 25 turns and a radius of 15 cm The horizontal component of the earth s magnetic field is 3 10 T The current required to produce a deflection of 45 in it is 2 1 2 A 1 0 29 A 3 3 6 10 A 4 014 A

A solenoid 1 5 m long and 0 4 cm in diameter possesses 10 turns per cm length A current of 5 A flows through it The magnetic field at the axis inside the solenoid is 1 2 x 10 T 2 2 10 T 3 4x 10 T 4 4 x 10 T

0 375 x 18 x 10 6 7 5 x 10 joules A magnetic dipole of magnetic moment M is placed on the axis of a current carrying circular la of radius R at a distance x from the centre Find the force acting on the dipole

partic A uniform magnetic field of magnitude 1 T exists in region y 0 is along k direction as shown A particle of charge 1 C is projected from point 3 1 towards origin with speed 1 m s If mass of Ay is 1 kg then co ordinates of centre of circle in which particle moves are pibs st 8 A 1 3 1 3 C 2 2 0 on abnowot ansig isin B 1 3 3 abusuot bata 3 D tax 0 s bi 2 2 2 a 3 1 B 1T hol A

A hollow conducting cylinder has an inner radius of a and an outer radius of b and carries a current I along the positive z direction Find H everywhere Use Ampere s circuital law Demonstrate clearly the correct usage of the Amperian paths

A coil having area A is placed in a magnetic field which changes from Bo to 4B in t seconds as shown in the figure The induced emf will be 1 Coil Plane is parallel to Bo 3Ao Bo t 2 4 A Bot 3 Zero 4 None B 24 2 3

There is a uniform magnetic field B normal to the xy plane A conductor ABC has length AB parallel to the x axis and length BC parallel to the y axis ABC moves in the xy plane with velocity vi vyj The potential difference between A and C is proportional to A 1 v l V l 2 v l V l 3 V Vyl B

Answer of 1 is option 2 of 2 is option 3 xplain 10 A steady eletric current is flowing through a cylindrical wire a the electric field at the axis of wire is zero c the electric field in the vicinity of wire is Zero 1 a b c 2 b c b the magnetic field at the axis of wire is zero d the magnetic field in the vicinity of wire is Zer 3 only c 4 only b For the hollow thin cylinderical current carrying pipe which statement is correct 1 magnetic field inside the pipe is not zero 3 electric field out side the pipe is zero 2 magnetic field out side the pipe is zero 4 electric field on the surface of pipe is zero

mple 9 A magnetic dipole of magnetic moment M is placed on the axis of a current carrying circular lo of radius R at a distance x from the centre Find the force acting on the dipole

A A horizontal overhead powerline is at height of 4 m from the ground and carries a current of 100 A from east to west The magnetic field directly below it on ground is consider wire to remain straight 2 5x 107T northwards 2 5x 107T southwards 5x10 6 T northwards

A 3 6 m long 9 0 g string is fixed at both ends and tightened until the wave speed is 80 m s a What is the frequency of the standing wave shown in the figure b What is the wavelength c What is the tension in the string 9301a sabie

A particle starts from rest from point P and follow a path PQ on the three surfaces as shown in figures If time taken by the particles in three cases are t t and 13 then select INCORRECT statement Ot3t t1 Oa a2a3 O t 1 13 O V1 V2 V3 AAA h 45 Case I Q Case II Q h 60 P h 30 Case III Q Marks 4 1

An electron is projected with uniform velocity along the axis of a current carrying long solenoid Which of the following is true O The electron will be accelerated along the axis O The electron path will be circular about the axis 1 point The electron will experience a force at 45 to the axis and hence execute a helical path O The electron will continue to move with uniform velocity along the axis of the solenoid

A proton and an electron travelling along parallel paths enter a region of uniform magnetic field acting perpendicular to their paths Which of them will move in a circular path with higher frequency O Electron O Proton Positron Negative proton D 1 po

magnetic field Statement P The magnetic field emerging out of the plane of the paper is denoted by a dot 0 Statement Q The magnetic field going into the plane of the paper is denoted by a cross 8 a Both P and Q are true b P is true but Q is false d Both P and Q are false c P is false but Q is true a O b O c d

The charge of a capacitor is O on the top plate only on both plates in the dielectric on the bottom plate only

1 A straight conductor of length ro carrying a current i is placed perpendicular to a long s conductor which carries a current i as shown in figure The force exerted by the segment of To on the long straight conductor is 1 Hiio In2 2T 2 Hii In2 TC 2r 3 Zero 4 2Hoii In2 TC

For a small circular current loop magnitude of magnetic field in the plane of the loop at a point distant x from centre of loop x R and magnetic dipole moment of loop is m IA is 1 B Hom X Ho m 4 x 2 B 3 B 4 B Mo 2m 4 x Hom R 21x 3

40 A plastic disc of radius R has a charge q uniformly distributed over its surface If the disc is rotated with a frequency about its axis then the magnetic moment of the disc is given by A B C qR f D none of these Hofq R ZqR 2

4 A student uses a simple pendulum of exactly 1m length to determine g the acceleration due to gravity He uses a stop watch with the least count of 1 s for this and records 40 s for 20 oscillations For this observation which of the following statement s is are true 2010 a Error AT in measuring 7 the time period is 0 05 s b Error AT in measuring T the time period is 1 s c Percentage error in the determination of g is 5 d Percentage error in the determination of g is 2 5

Column II gives certain systems undergoing a process Column I suggests changes in some of the parameters related to the system Match the statements in Column I to the appropriate process es from Column II 2009 Column I A The energy of the system is increased p B Mechanical energy is provided to the system which is q converted into energy of random motion of its parts Column II System A capacitor initially uncharged Process It is connected to a battery System A gas in an adiabatic container fitted with an adiabatic piston Process The gas is compressed by pushing the piston C Internal energy of the system is converted into its r System A gas in a rigid container mechanical energy D Mass of the system is decreased t Process The gas gets cooled due to colder atmosphere surrounding it s System A heavy nucleus initially at rest Process The nucleus fissions into two fragments of nearly equal masses and some neutrons are emitted System A resistive wire loop Process The loop is placed in a time varying magnetic field

42 A proton and an electron both moving with the same kinetic energy enter into a region of magnetic field directed perpendicular to the velocity of the particles They will now move in circular orbits such that A their time periods will be same B the time period for proton will be higher C the time period of electron will be higher D their orbital radii will be same

2 A left circularly polarized light beam of wavelength 600 nm is incident on a crystal of thickness d and propagates perpendicular to its optic axis The ordinary and extraordinary refractive indices of the crystal are n 1 54 and n 1 55 respectively The emergent light will be right circularly polarized if d is a 120 m b 60 m d 15 m SKE c 30 m

SolveLancer Test A rectangular coil of area 1 m and resistance 5 placed in a magnetic field B applied perpendicular to the plane of the coil Which of the following is true about the direction and magnitude of the current 20 T s SolveLancer Test dB dt a 4 A Clockwise b 8 A Clockwise c 8 A Anticlockwise d 4 A Anticlockwise B coil

5 Through a straight conducting wire of length 1 m 2 A cur rent is flowing If the wire is placed normal to a uniform magnetic field of strength 10 3 T what will be the mag netic force acting on the wire 2 10 N

3 Two long parallel straight wires X and Y separated by a distance of 2 5 cm in air carry currents of 5 A and 2 5 A respectively in opposite directions Calculate the magni tude and direction of the force on a 10 cm length of the wire Y CBSE 04 10 5N repulsive normally away from X

The circular wire in figure below encircles solenoid in which the magnetic flux is increasing at a constant rate out of the plane of the page Path 2 A 0 0 B Eo 0 C EO E0 DI wire Path 1 The clockwise emf around the circular loop is so By definition a voltammeter measures the voltage difference between the two points given by Vb V E ds We assume that a and b are infinitesimally close to each other The values of Vb Va along the path 1 and Va Vo along the path 2 respectively are

6 The radius of a circular coil of 100 turns is 5 cm and it car ries a current of 10A What torque will act on the coil when its plane is kept at 30 with a uniform magnetic field of 0 039 N m 0 01 T