Electromagnetic Induction Questions and Answers

Find the magnetic energy stored by a 4 50 mH inductor when the current through it is 13 0 A Part 1 Give the equation used for finding the magnetic energy stored in an inductor in terms of its inductance L and the current flowing through it I U Part 2 What is the magnetic energy stored in the inductor

imple pendulum of mass m length I and charge q suspended in the tric field produced by two conducting parallel plates as shown The value of ection of pendulum in equilibrium position will be Q V Medium K m q air V E A o

50 Current in the long straight wire is decreasing with time The induced current in loop 1 and 2 are 2 1 Clockwise in loop 1 as well as in loop 2 2 Clockwise in loop 1 and anticlockwise in loop 2 4 3 Anticlockwise in loop 1 and anticlockwise in loop 2 Anticlockwise in loop 1 and clockwise in Joon 2

A solenoid of inductance 100 mH and resistance 4 20 2 is connected to a cell of emf 10 V at t 0 If the energy stored in the inductor when the 1 64x time t 5 ln2 milli seconds is the value of x J then find

A coil of area 100 cm is kept at an angle of 30 with a magnetic field of 10 1 T The magnetic field is reduced to zero in 10 4 s The induced emf in the coil is a 5 3 V b d 50 3 V 50 0 V

4 A circular loop is lying inside a magnetic field B as shown in figure At 0 it starts moving out of fiel 2a with constant speed v E m f induced in the loop at time is V a vB 2avt v 1 b 2vB 2avt v 1 c v Bt d 2vB 2avt v 1 X X Xx X X X x X X x X X X X X

he horizontal component of earth s magnetic field at a certain location is 2 6 X 10 T and points notional emf appears in 0 80 m vertical radio antenna of a car travelling north with a speed of 95 6 5 X 10 4 V OV 55 X 10 4 V 5 5 X 10 6 V

2 For observer P current in loop is clockwise the moment K is plugged The induced current in loop observed is A 1 Zero 2 Anti clockwise 3 Clockwise B 10

30 A plane loop is shaped in the form as shown in figure with radii a 20 cm and b 10 cm and is placed in a uniform time varying magnetic field B B sin oot where B 10 mT and 100 rad s The amplitude of the current induced in the loop is A if its resistance per unit length is equal to 50 x 10 m The inductance of the loop is negligible X X X XXX X X XB

An equilateral conducting loop is placed in a time dependent magnetic field in a cylindrical region as shown in the figure The magnetic field is given as B Bot where t is time in second and B is 2 tesla per second The side of triangle is 1 m and resistance of each side is 10 Work done per unit positive charge along PQ will be 1 V value of x is X 3 P X X

cting loop of resistance R and radius r has its centre at the origin of the coordinate system in a magnetic field of induction B When it is rotated about y axis through 90 the net charge flown in the loop is directly proportional to y 1 R 1 3 1 2 R X

3 The circular wire loop of radius R is placed in the x z plane with the centre at the origin Another circular loop of radius r r R having 32 turns is placed with its centre at y 3R The plane of the second loop makes an angle of 60 with the y axis The mutual inductance between the loop is stionpa 1 2 3 4 R H R P 60 R

1m X X X X X X X X XXXX X X X X 1m U X X X X X X Consider the figure given above 1 2m Frame PQRS is made of wire and is rectangular and uniform in nature The frame PQRS has a straight connection between E and F made of the same wire PUVS is a square of side 1m and UQ VR 0 5m The complete circuit is placed in a uniform magnetic field steadily increasing in nature Magnetic field is directed into the plane of the paper and normal to it 1T s is the rate by which the magnetic field is changing The resistance for a given per unit length of the wire is 10 m The magnitude and direction of the currents in the segment UV is R A 1 22 A from V to U B 7 22 A from U to V C 6 22 A from V to U D 3 22 A from U to V

questions Each question has 4 choices 1 2 Read More In a uniform magnetic field of induction B a wire in the form of a circle of radius rrotates about the diameter of the circle with angular frequency w The axis of rotation is perpendicular to the field If the total resistance of the circuit is 2R the maximum power generated is Bar 0 2R B r 0 8R Biro 2R

Radius of current carrying coil is R Then ratio of magnetic fields at the centre of the coil to the axial point which is R 3 distance away from the centre of the coil 1 1 1 2 1 2 3 1 4 4 8 1 MG0005

7 A load of 300 kW with power factor 0 65 lagging has the power factor improved to 0 90 lagging by parallel capacitors How many Kvar must these capacitors furnish and what is the resulting percent reduction in apparent power

A charged capacitor of capacity 30 F is connected to 27 mH inductor What is angular frequency of free oscillations of the circuit O 1500 rad s 1 O 1111 rad s 1 Read More O 1616 rad s 1

There are two coils X and Y as shown in the figure What is the direction of the induced current in the coil Y when the switch S is pressed X A YOU B Y C Anticlockwise Clockwise S C O Alternating current is produced

16 In the circuit shown below the key is pressed at time t 0 Which of the following statement s is are true JEE Adv 2016 Paper 2 40 F www 50 k www 25 KQ 20 F Key 5 V Ke A The voltmeter displays 5 V as soon as the key is pressed and displays 5 V after a long time B The voltmeter will display 0 V at time t In 2 seconds C The current in the ammeter becomes 1 e of the initial value after 1 second D The current in the ammeter becomes zero after a long time

A semi circular conducting wire PS of radius r is placed in a plane perpendicular to a uniform magnetic field of intensity B as shown Now the loop is moved in its own plane at a constant velocity v parallel to its diameter POS Then the induced potential difference between S and a point M which is located at an angular position 0 VM Vs is given by S A Bur sin 0 B Bur sin 0 C Bur cos 0 D v Ok Bur cos 0

A solenoid of length 0 2 m has 1000 closely wound turns Area of cross section of the solenoid is 2 10 3 m A coil X of 200 turns is wound around its central cross section The rate of change of current is 7 amp per 0 11 sec Find the emf induced in the solenoid Options O 0 16 V O 0 32 V O 0 24 V O 0 48 V

A particle of specific charge unity is released from origin It is to move through space between charged capacitor plates having magnetic field of B 1T k and electric field E 1V mj as shown in the figure particle just escapes collision from point P and Q Values of statements in column l are in column II in SI units Match them correctly 0 d 1 0 Q fag de c ad yg hu g ya fa a au fa ten 33 0 d a B 1V mj 1 far pa Q cache As dual 21 c A4 ay ARTI b Column l d a f g 2 Bat gradu Q Qach gut au d Time taken to reach Time taken to cattain Vy max B max B Ratio of time taken to attain Vx max to vy Y TY P 2 q S r 2 t Column II TT 2 2 T 3 Xx 1 0 X

e 7 34 A conducting rod is rotating about a fixed point as shown in the figure with angular velocity 1 A BomL 2 B 0L L 2 If the whole setup is in perpendicular uniform magnetic field Bo then the potential difference between point A and B VA VB is 2 X wwwww B L 4 i 1 wwwwwww

A conducting rod PQ of length 2 m is moving at a speed of 2 ms making an angle of 30 with its length A uniform magnetic field B 2 T exists in a direction perpendicular to the plane of motion Then X X X 2 X P X X X X X YOU A Vp Vo 8 V B Vp Vo 4 V X X X X X X 30 X X X X X X

Example 11 The OH radical has a moment of inertia of 1 48 x 10 47 kg m Calculate its internuclear distance Also calculate for J 5 its angular momentum and angular velocity Detemine the energy absorbed in the J 6 J 5 transition in m 1 and joule molecule

The magnetic field through a loop of area 1 m and of resistance 10 changes with time as shown in figure The induced current in the loop at t ls AB T fo Options O 0 1 A O 0 2 A O 0 4 A 01A t s

3 A conductor ABOCD moves along its bisector with a velocity 1 m s through a perpendicular magnetic field of 1 Wb m as shown in figure If all the four sides are 1 m length each then the induced emf between points A and D is B AX 0x 2 1 0 3 0 71 volt Cx v 1 m s 2 1 41 volt None of those

resistance as shown in figure The two rails are connected by a wire of resistance R If the conductor is allowed to fall freely and friction between the conductor and rails is negligible then choose correct statement R 0 velocity of conductor is V mgR B 2 acceleration of conductor is power supplied by gravity is 1 ge ma m g R B 2 XXX X X X X X X XXX XX X X X X X B 21 e ma X XX X X X X X X X X 8221 1 e mR XX X X X X X X X X X X X XX Xxx

21 8 UTM 8 UTM I t 900 R Cet UTM UTM TM 5 marks ii The series are connected with inductance 350 henry and the resistance is 18 ohms Find I t if the initial current I 0 0 Calculate the current I t at time t 1 minute UITM 11TM 5

The north pole of a long horizontal bar magnet is being brought closer to a conducting loop in a vertical plane al the perpendicular direction as shown The induced current in the conducting loop as seen from magnet side is Options O Clockwise O Anticlockwise O Horizontal O Vertical

A conducting disc of radius 10 cm is rotating perpendicular to magnetic field at an angular frequency of 40 rad s If the emf induced between its rim and axis is 4 mV find the magnitude of magnetic flux density Options O 0 01 T 0 0 02 T O 0 03 T O 0 04 T

A magnetic field of induction 2T acts at an angle of 30 to the plane of the circular coil of area 0 4 m having 20 turns The coil is removed from the field in 0 1 sec Find the induced emf in the coil Options O 400 V O 600 V O 800 V 0 500 V

A square loop of wire of side length 10 cm is placed at angle of 45 with a magnetic field that changes uniformly from 0 1 T to zero in 0 7 second The induced emf in the loop is O 25 mV 01mV O 4mV O Zero

10 kHz 100 pH m 500 u H leee 2 0 mH Figure 13 1 if the frequency in the circuit in Figure 13 1 is increased to 100 kHz what is the total inductance O 5200 mH 1600 mH 602 mH 2600 KH

TA 3X6M 18 M 1 A long toroidal core has an effective diameter of 10cm is wound with 2300 Turns meter Determine the value of the mutual inductance between the two coils if the secondary coil has 300 turns CO2

A conducting loop of resistance R and radius r has its center at the origin of the co ordinate system in a magnetic field of induction B When it is rotated about Y axis through 90 net charge flown in the coil is directly proportional to A B C r 2 B R D r

Assertion The mutual induction between the two coils infinitely apart is zero Reason If the mutual induction between the two coils is zero it means that their se inductances are also zero 1 Point Assertion is correct reason is correct reason is a correct explanation for assertion Assertion is correct reason is correct reason is not a correct explanation for assertion Assertion is correct reason is incorrect AND Assertion is incorrect reason is correct

18 A conducting circular loop is placed in a uniform magnetic field 0 04 T with its plane perpendicular to the magnetic field The radius of the loop starts shrinking at 2 mm s The induced emf in the loop when the radius is 2 cm is 2 Points 4 8 V 0 8 V 1 6 V

168 Electromagnetic Induction 6 If the current in long straight current carrying wire increases with the time then direction of induced current in circular loop is 1 Clockwise 2 Anticlockwise 3 First clockwise and then anticlockwise 4 First anticlockwise then clockwise In the given figure shown below a conducting circular loop of radius T is placed in a uniform and perpendicular magnetic field B A metal rod OA is pivoted at centre O of the loop The other end A of rod touches the loop The rod OA and loop are resistanceless but a resistance R is connected between O and fixed point e of loop The rod is rotated with angular velocity w The current in resistance R is

A circular loop of radius of 10 cm is placed perpendicular to a uniform magnetic field with an unknown strength The magnitude of the flux through the loop is 5 x 10 3 Tm What is the magnitude of the magnetic field a 0 2 T b 0 1 T OC 0 16 T d 0 13 N

In a series RC circuit a resistance and capacitance are connected in series in such a manner it takes 220V ac supply the values of resistance and capacitance are 20ohm and 0 6 microfarad The supply frequency is 50Hz of the circuit Determine total impedance of the circuit

A non conducting ring of mass 4 kg is uniformly charged with 4C m and kept on rough horizontal surface with friction coefficient 4 A time varying magnetic field B Bot is applied in a circular region of radius a a perpendicular to the plane of ring as shown in figure Find out the time in sec when ring just starts to rotate on surface take a 5cm and g 10m s Bo 125 SI Unit B 21 Question Type Numerical Type 1

5 29 A rectangular loop of wire is placed in a uniform magnetic field B acting normally to the plane of the loop If a man attempt to pull it out of the field with velocity v as shown in figure 5 338 calculate the power required for this purpose X X X 1 X X F X Figure 5 338 X X

The circular wire loop of radius R is placed in the x z plane with the centre at the origin Another circular loop of radius r r R having 32 turns is placed with its centre at y 3R The plane of the second loop makes an angle of 60 with the y axis The mutual inductance between the loop is 1 2 H r R Hor TR Hor VZ 60 7 3R R C X

or decreasing current 6 An emf induced in a secondary coll is 2000 V wher current breaks in the primary The mutua Inductance is 10 H and the current reaches from maximum current to Zero in 103 s in primary Calculate the maximum current in primary befor the break 1 0 4 A 3 0 2 A 2 0 3 A 4 0 6 A

Consider the following electric circuit At a given instant the current through the battery is 2 A and increasing at a rate 1 A s The value of emf of the cell is assume the cell to be ideal mmm 2 H 4 V 2 V 6 V 10 V www 492

Students of automobile engineering are working on a project as they require to analyze and compose a circuit in which a coil having inductance of 0 03H and resistance of 502 connected across 200V 50Hz supply in such a manner that when a resistance of 50 is connected in series with capacitance it takes same current i Evaluate total impedance of the circuit ii Determine the power factor of the circuit

In gravity free space a uniform horizontal magnetic field exists into the plane of paper only in the region above xy A uniform vertical downward electric field of magnitude E a exists only in the region below xy as shown in figure The bob of simple pendulum of length L with point of suspension on line xy and having mass Im and charge q is given horizontal velocity at the lowest point such that the tension in string at this point is T 5qa Fixed L A q y 3 Af yg a fau yracu xy a had huu da B E a TRHU Ych 4x4 KETERA e faya a fa terfy 341 BO e m tu xy uz Anta far and Latis ura 4 ga nach c qaz Add fa g u42 34 ug z faj f Ga mich 34 far 42 zzf ada 5 qa FRETE L y E a q BO y E a The magnitude of magnetic field B such that as the bob enters the magnetic fiel the string becomes slack and then it passes through the point of projection is Bu yrachu a ude hem zem am ad a Me uz u tuu far qurd Correct Answer 2ma qL 2ma qL The magnitude of magnetic field B such that as the bob enters the magnetic fiel the string becomes slack and then it passes through the point of suspension is 8ma qL Buku 7 A mac yracu a f ude hem zz am ad ar Me ug Adtaa far quedi 2 Correct Answer 8ma qL The maximum magnitude of magnetic field such that the bob of the pendulum still completes the vertical circle is 4am qL i f c Ru fch t sa

Problem 1 The h parameters of a transistor are hie 1100 hfe hre 5 x 10 4 and hoe 50 25 x 10 6 A V If the transistor is used as a CE amplifier with load resistance 10 kN and effective source resistance 600 find the current gain voltage gain input resistance output resistance and power gain Calculate the output voltage for a signal voltage of 10 mV

1 Two co axial solenoids shown in figure If key of primary suddenly opened then direction of instantaneous induced current in resistance R which connected in secondary Ottic 4F0 1 L to N 3 Alternating L R N 2 N to L 1 Zoro