Electromagnetic Induction Questions and Answers

The magnetic field in the region is decreasing in such a way that dB dt y If resistance per unit length of the loop shown is A then the current flowing in the loop is given by 1 2 ry X X X X X X X x X X PA x X x Clockwise 2 ry 2 Anticlockwise X x 3 Clockwise 4 Anticlockwise X X X x X X X x X X X X X X

A thin non conducting ring of mass m radius R carrying uniformly distributed charge q is placed on smooth horizontal plane There exist an uniform time varying magnetic field in a cylindrical region directed vertically upward Magnitude of magnetic field varies with time as B Bot tesla where n is a number Centre of ring coincides with centre of cylindrical region Ring was at rest at t 0 Neglect the magnetic field produced due to any kind of motion of ring Answer the following 2 questions Choose the correct option s regarding magnitude of induced electric field at the periphery of the ring EA EA if n 21

View In English A conducting rod with resistance r per unit length is moving inside a vertical magnetic field at constant speed v on two horizontal parallel ideal conductor rails The ends of the rails are connected to a resistor R The separation between the rails is d The rod maintains a tilted angle 8 to the rails Find the external force required to keep the rod moving 1 4 F F F F B d v R dr B d v R dr sine B d v sine R dr sine B d v cos 0 R dr cos 6 d B R

th 3 2Bw A semicircular loop of radius R is rotated with an angular velocity to perpendicular to the plane of a magnetic field B as shown in the figure Emf induced in the loop is 4 Zero 1 BOR 3 3 BWR 2 12212 R le X x X X X x X X x x x B x 1 2 BOR 2 BOR 4 is required to move a conducting loop through a non uniform magnetic field at 2 ms 1 Th

A proton carrying 1 MeV kinetic energy is moving in a circular path of radius R in uniform magnetic field What should be the energy of an a particle to describe a circle of same radius in the same field Mains 2012 2 MeV 1 MeV 0 5 MeV 4 MeV

A long wire carrying alternating current i io cos t is kept along the axis of a toroid The inner and outer radii of the toroid are R and R respectively The toroidal loop has rectangular cross section with N turns and height h If R 4R io 3 A N 1000 and h 2 mm Then the maximum emf induced in the loop is R D R

3 91 x 10 4 kg m sec 4 91 x 10 kg m sec Which of the following is not a unit of 4 self inductance 1 Weber Ampere 3 Joule Ampere 2 Ohm Second 2 4 Joule Ampere 5 Select the correct statement regarding stream line flow 3 91 x 10 4 kg m sec 4 91 x 10 kg m sec fara a fa 1 difer 3 to con 2 314 us 4 2 AH B T

Faraday s Law of induction 11 The loop moves towards a region of magnetic field Draw graph of i ve direction is marked in figure time Speed of coil is constant and equal to v 2a 2a Bo

2 A square shaped coil of side 20 cm is rotating at 60 revolutions per minute in a magnetic field of 1001 number of turns is thousands find maximum emf developed across the coil 1 8m kV 2 kV 3 0 5m kV 4 1 5m kV

12 A square shaped coil of side 20 cm is rotating at 60 revolutions per minute in a magnetic field of 100 number of turns is thousands find maximum emf developed across the coil 1 8 kV 2 kV 3 0 5 kV 4 1 5 kV

A particle having mass m and charge q is projected with a velocity v making an angle with the direction of a uniform magnetic field B Calculate the magnitude of change Bosa in velocity of the particle after time t m 2 qB

A thin uniform conducting rod of mass M and length L oscillates in a vertical plane about a fixed horizontal axis passing through its top end The rod is oscillating with angular amplitude 00 A uniform horizontal magnetic field B perpendicular to the plane of the oscillation is switched on a Calculate the maximum emf induced between the ends of the rod b If the rod has a finite thickness any real life rod will definitely have a thickness what difference in oscillation is expected in absence of magnetic field and in presence of magnetic field Describe qualitatively

During the propagation of electromagnetic waves in a medium O Electric energy density is double of the magnetic energy density O Electric energy density is half of the magnetic energy density O Electric energy density is equal to the magnetic energy density O Both electric and magnetic energy densities are zero

In an LCR circuit shown in the following figure what will be the readings of the voltmeter across the resistor and ammeter if an a c source of 220 V and 100 Hz connected to it as shown C 1000 300V 300V F 220 V 100 He 800 V 8 A O 110 V 1 1 A O 220 V 2 2 A O 300 V 2 2 A

A rectangular frame of negligible resistance with capacitor of capacitance C is placed nearby an infinitely long wire carrying current I lo sin wt wire and frame being in same plane Select correct alternative s U Maximum charge on capacitor is Charge on capacitor at t 0 is Current in frame is minimum at t Maximum current in frame is 4 olowen2 7 3 olowen 2 TT 3w 2w oloen2 7 C C C 4 2m 2m 4m

Q1 A coil of wire of area 5cm2 has 500 turns and self inductance of 100mH a Calculate the length of the coil b What will be the self inductance of another similar coil with 200 turns c How will the value of self inductance be affected if an iron rod is inserted in the coil 2

D 26 One solenoid is centered inside another The outer one has a length of 50 0 cm and contains 6750 coils while the coaxial inner solenoid is 3 0 cm long and a cm in area and contains 150 coils The current in the TRA outer solenoid is changing at 3000 A s The emf induced in the inner solenoid is V 4121010 Round off to two decimal places

A circular insulated copper wire loop is twisted to form two loops of area A and 2A as shown in the figure At the point of crossing the wires remain electrically insulated from each other The entire loop lies in the plane of the paper A uniform magnetic field 3 points into the plane of the paper At t 0 the loop starts rotating about the common diameter as axis with a constant angular velocity w in the magnetic field Which of the following options is are correct XX X X X X XX X x X X xx X area Ac X DO area 2A X x X xxxx in the loop is proportional The emf induced to the sum of the areas of the two loops The rate of change of the flux is maximum when the plane of the loops is perpendicular to plane of the paper The net emf induced due to both the loops is proportional to cos wt The amplitude of the maximum net emf induced due to both the loops is equal to the amplitude of maximum emf induced in the smaller loop alone

A copper disc of radius 0 1 m rotated about its centre with 10 revolutions per second in a uniform magnetic field of 0 1 tesla with it s plane perpendicular to the field The e m f induced across the radius of disc is A B 10 volt 2 10 volt CTX 10 2volt 2 x 10 2 rolt

A coil of copper wire is connected in series with a bulb a battery and a switch When the circuit is completed the bulb lights up immediately The circuit is switched off and a rod of soft iron is placed inside the coil On completing the circuit again It is observed that 1 Bulb is not so bright 2 There is a slight delay before bulb lights to its normal brightness 3 The bulb is initially bright but gradually becomes dim 4 The bulb is brighter than before

Q3 A conducting circular loop is placed in a uniform Magnetic Field such that it s plane is perpendicular to the field having strength 0 5 T If the radius of the coil decreases steadily at the rate of 10 2 m s What will be the magnitude of induced EMF when Radius of coil is 7 cm a 4 4 x 10 3 V b 4 4 x 10 4 V c 2 2 x 10 5 V d 2 2 x 10 3 V

5 A magnet N S is suspended from a spring and when it oscillates the magnet moves in and out of the coil C The coil is connected to galvanometer G Then as the magnet oscillates G shows eeeeeeeeee S 1 No deflection 2 Deflection to the left and right but the amplitude steadily decreases 3 Deflection to the left and right with constant amplitude 4 Deflection on one side

A copper ring having a cut such as not to form a complete loop is held horizontally and a bar magnet is dropped through the ring with its length along the axis of the ring The acceleration of the falling magnet is g Less than g More than g

9 An aluminium ring B faces an electromagnet A The current I through A can be altered Then which of the following statement is correct 14 A B 0 1 If decreases A will repel B 2 Whether increases or decreases B will not experience any force 3 If increases A will repel B 4 If increases A will attract B

22 In the figure given below the magnet is moved towards the stationary coil with speed v and induced emf in the coil is E Now if magnet and coil both recede away from one another each moving with speed 2v Same position then induced emf in the coil will be 1 4 S 0 N

Two capacitors C C of capacitance 10 x 102 F each and an inductor L of inductance 2 x 10 2 H are connected in series as shown in the figure Initially charge on each capacitors are 4 3 C At t 0 switch S is closed and at 1 400 sec switch S is also closed The maximum charge on capacitor C during LC oscillation is A 3 C B 6 2 C C 3 3 C D 6 3 C 000000

A long solenoid of 20 turns per cm has a small loop of area 4 cm placed inside the solenoid normal to its axis If the current by the solenoid changes steadily from 4 A to 6A in 0 25s what is the average induced emf in the loop while the current is changing

18 The electric field part of an electromagnetic wave in a medium is represented by Ex 0 N Ey 2 5 cos 2 x 106 rad t x 10 2 rad X S m 3 E 0 The wave is AIPMT Prelims 2009 1 Moving along x direction with frequency 106 Hz and wavelength 100 m 2 Moving along x direction with frequency 106 Hz and wavelength 200 m 3 Moving along x direction with frequency 106 Hz and wavelength 200 m 4 Moving along y direction with frequency 106 H7 and wavelength 200 m

2 A parallel plate capacitor is charged by a battery as shown in the figure If two circular amper an loops x and y are drawn then B di will be zero along 1 x only P101 X 2 y only

figure shows three circuits with identical batteries inductors and resistors Rank the circuits in the decreasing order according current through the battery i just after the switch is closed and ii a long time later www www www A B 0 1 1311 11 0 1 1 13 11 1 1 13 1 0 11 12 13 1 1 1 13 1 0 1 1 13 1 0 1 13 1 1 0 11 12 13 1 www 1 2 3

n a permanent magnet at room temperature Magnetic moment of each molecule is zero The individual molecules have non zero O magnetic moment which are all perfectly aligned Domains are partially aligned All domains are perfectly aligned

The flux linked with a circuit is given by 312 7 The graph between time x axis and induced emf y axis will be A straight line Circle Parabola hr mir None of these

Energy stored in an inductor of inductance L will be is current O 2 LR 1 2 212 IN O 1 L1

A 5 cm x 12 cm rectangular coil with number of turns 600 is placed in uniform magnetic field of strength 0 1 T The maximum magnetic torque acting on it when a current of 10 5 A is passed through it is closest to O 3 6 x 10 6 Nm 2 4 x 10 5 Nm 2 4 x 10 6 Nm O 1 8 10 5 Nm

Q6 In a region of free space the electric field at some instant of time is E 801 32j 64k V m and the magnetic field is B 0 21 0 08 0 29k T The pointing vector for these fields is a 11 52 28 8 b 28 8 11 52

Magnetic field B 1T is in a circular region of diameter 1m A rod initially located as diame starts moving perpendicular to itself with speed v 10 cm s Find the EMF generated in e of rods at t 3s in mV

A thin semi circular conducting ring of radius R is falling with its plane vertical in a horizontal magnetic field B in figure At the position MNQ the speed of ring is v The potential difference developed across the ring is N X X xl X M X Zero R X X X Q O BTR and Mis at a higher potential BRV and Q is at higher potential

A thin semi circular conducting ring of radius Ris falling with its plane vertical in a horizontal magnetic field B in figure At the position MNQ the speed of ring is v The potential difference developed across the ring is N X M O Zero O X X 1 2BT R BTR and Mis at a higher potential OBRV and Q is at higher potential

A solenoid has 2000 turns wound over a length of 0 3 m The area of its cross section is 1 2 10 m Around its central section a coil of 300 turns is wound If an initial current of 2 A in the solenoid is reversed in 0 25 s then the magnitude of emf induced in the coil is equal to O 6 10 4 V 4 8 x 10 V O 6 10 V

A long solenoid of radius 10cm is surrounding coaxially by a larger coil of radius 20cm and length 5cm the longer coil has 1000 turns per metre and the larger coil has 200 turns Current in longer solenoid is changing from 5A to zero in 1 second Then charge that flows in larger coil when its circuit is closed with a resistance of 10002 is C Consider 10

Two coaxial solenoids have radii 3 cm 2 cm and lengths 60 cm 100 cm and number of turns 200 300 respectively Their geometrical centres are coinciding Their mutual inductance is n 10 1 7 2 x 10 3 H 2 4 8 10 H 3 9 6 10 5 H 4 2 4 x 10 5 H

Consider the network as shown The current i depends on time t as i 10e 2t Then A 5 V ww00000 22 2H B At t 0 VA V 15 V At t 0 VA V 15 V B 1251 3 At t VA VB 5 V

A rectangular loop made of flexible conducting wire carrying clockwise current is placed in uniform magnetic field as shown Choose the corred alternative X B x X X X b X The loop develops induced anti clockwise current for a short time B a b ab R TC Ja 2 The loop finally has area equal to a b 4 Induced charge flown through the loop is where R is resistance of the loop 4 Centre of mass of the loop does not change

Self inductance of solenoid is L which is mad by a wire of length then length of solenoid is 1 Ho 4x L 3 T 4Le Ha 2 4RLE Ho Hol 4ml

The wires P Q1 and P Q2 are made to slide on the rails with the same speed 10m s If P Q moves towards left and P2Q2 moves towards the right then the electric current in the 1952 resistor is X X X X X X 4 cm 2 1 Zero X X X 2 10 mA 4 1mA 3 0 1 MA P P QxQ x XX X 19 B 1 0 T x X X X X X

a rectangular conducting loop having side length a and b The mutual inductance of the given system is 2 31 Ha 27 In b a x a H b x a In 2 x a 212 b

A metallic rod of length 1 resistance R is free to rotate about one of its ends over a smooth rigid circular metallic frame of radius in an inward magnetic field of induction B What torque should be applied by an external angent to rotate the rod with constant angular velocity w

5 70 On a smooth horizontal table a disc is placed with non conducting ring with uniformly distributed charge q fixed on its circumference Both disc and ring are of mass m and radius r If a uniform magnetic field of induction B which is symmetric with centre of disc is switched on in vertically downward direction find the angular speed attained by disc due to this aR

cting rings of radii r and 2r are moving in opposite direction with velocities 2v and v respectively as shown in figure on a conducting surface S There is a uniform magnetic field of magnitude B existing perpendicular to the plane of the rings The potential difference between the highest points of the two rings is 2v 1 Zero 31 AnR BO S 2 2Bvr

Q 90 current urther resulting curve 3 Rate n ving best represent the 1 Rate n