Electromagnetic Induction Questions and Answers

5 6 The primary winding of a transform 200 turns whereas its secondary has 2000 turns If the primary is co to an ac source of 20 V and 60 H secondary will have output of INCERT 1 200 V and 6 Hz 2 2 V and 60 Hz 3 200 V and 60 Hz 4 2 V and 6 Hz

iii Two infinite long straight parallel wires A and B are separated by 0 1m distance and carry equal currents in opposite directions A square loop of wire C of side 0 1m lies in the plane of A and B The loop of wire C is kept parallel to both A and B at a distance of 0 1m from the nearest wire Calculate the EMF induced in the loop C while the currents in A and B are increasing at the rate of 10 A s Also indicate the direction of current in the loop C 2 105 in G 3 volt clockwise

4 Two circular coils one of small radius r and other of larger radius R r R are placed co axially with centres coinciding The mutual inductance of the arrangement is INCERT PO 221 1 HORR2 2r 3 H RrR r R 2 Horr 2R 2 0r R

A 20 cm long conductor carrying a current of 10 A is kept perpendicular to magnetic field of 0 6T The mechanical power required to move conductor with a speed of 1 ms is NCERT Pg 215 2 1 5 W 4 0 4 W 1 1 2 W 3 0 6 W

A square loop of edge 20 cm and resistance of 1 92 is placed vertically in horizontal plane A uniform magnetic field of 0 5T is set up across the plane in the direction at 45 to the plane The magnetic field is decreased to zero in 0 2 s at a steady rate Calculate magnitude of current induced in this time interval INCERT Pg 208 ra 2 50 mA

A circular loop with its plane parallel to plane of paper is entering into uniform magnetic field directed into the plane of paper perpendicularly The loop is moved at constant speed V Then NCERT Pg 212 1 No emf will be induced in the coil 2 Induced emf is constant in magnitude only 3 Induced emf is varying with time 4 Induced emf is constant in magnitude as well as in direction

A square loop of side length L meter lies in x y plane in a region where the magnetic field is given by B B i 2 3k T B is positive constant The magnitude of magnetic flux passing through square is NCERT Pg 207 edi 1 5 B L Wb 2 3 B L Wb 3 14 B L Wb d

A short circuited coil is placed in a time varying magnetic field Electrical power is dissipated due to the current induced in the coil If the number of turns were to be quadrupled and the wire radius halved the electric power dissipated would be 1 Halved 3 Doubled 2 The same 4 Quadrupled

5 20 Two parallel conducting rails separated by a distance are fixed on a plane surface inclined at an angle a to the horizontal as shown in figure 5 336 Rails are connected at the bottom by a resistance R A copper rod of mass m slides without friction on the rails due to gravity A uniform vertical field B exists throughout the region Find the steady state velocity of the rod Show that the rate at which thermal energy is produced in the circuit is equal to the rate at which rod is losing gravitational potential energy What will happen if the direction of B is reversed mgr sin a A D B as www R Figure 5 336 C B

In an electromagnetic free space the root mean square value of the electric field is E 1 6Vm The peak value wave in rms of the magnetic field is O examsnet com 2017 NEET O2 83 10 T O 0 70 10 T O 4 23 10 T

Ans 3 28 A tan 5 5 4 A bulb of resistance 10 Q2 connected to an inductor of inductance L is in series with an AC source marked 100 V 50 Hz If the phase angle between the voltage and the current is 4 radian find the value of L ABY 1 Ans H

S Consider an infinite one dimensional wire carrying a uniform current I as shown in the figure A square loop of side a is initially placed such that the center of the loop is at a distance R from the wire where R The square loop is then moved rightwards with a uniform speed u as shown in the figure What is the induced emf in the loop as a function of time t 3 o Ia v 4 R vt X 1 2 X 3 Hola v 2 R vt 2 3 ola v 2 R vt 2 Hola v a 4 71 a

A ring of circular cross section is made of material of resistivity p The inner an outer radii of ring are a and 2a respectively and its thickness is h The ring placed in a time varying magnetic field B kt where k is a constant which parallel to the axis of the ring as shown in the figure The induced current in th ring is B kt B C D a 2a 3kha 4p 2 3kha 2p 5kha 4p 5kha 2p

5 58 Along straight wire is parallel to one edge of a rectangular loop as shown in figure 5 310 If the current in the long wire varies with time as I Ie what will be the induced emf in the loop at t t A Hobl In d a TT In d a 2 obl b a Figure 5 310 B d a d Hobl 2 t Hobl In d In

A very long straight conductor and an isosceles triangular conductor lie in a plane and are separated from each other as shown in figure If a 10 cm h 10 cm and b 20 cm then the coefficient of mutual inductance of system will be O2 10 8 In 2 O O 2 10 1 In 2 4 x 10 8 In 2 4 x 10 8 1 In 2 a

A rectangular conducting loop B has its side lengths equal to b and a b In the plane of the loop there is another very very small loop A in shape of a square side length x x a Loop A is placed symmetrically with respect to B with its centre at a distance a from one of its longer side see figure There is a current i i di loop A which is made to increase at a constant rate of a As1 Choose the correct statement s dt P

5 59 A constant voltage is applied to a series RL circuit by closing the switch The voltage across inductor of inductance 2H is 20V at t 0 and drops to 5V at 20ms The value of R is A 100 In 20 100 In 40 B 100 1 In 2 D 100 1 In 4

The circuit was under steady state At t 0 switch K is closed the value of s found to be x times The value of x is K R www L celller 2R olo for inductor just after key K is clo

When a magnet suddenly exits the center of a solenoid coil an induced voltage EMF appears If the coil is part of a circuit containing a galvanometer in which direction do you expect the needle to deflect draw the current direction on the coil

eld ce ely 1 25 A conducting rod of length rotates about its one end with angular velocity o Potential difference between A and B Find V Take m points of rod as shown in figure 1 404 is V AB AB as mass of electron and e is the charge of electron A S mw 1 3mw 1 1 2 1 2 A Figure 1 404 B 3mw 1 4e D Zero B

A metallic wire ABC is placed along the curve y x Coordinates of point A B and C are 1 1 0 0 and 1 1 respectively This wire is rotating with angular velocity 4 rad s about z axis in anticlockwise sense There exists a uniform magnetic field B 2 Tesla directed towards negative z axis Then A emf between points B and C on the wire has magnitude 8 Volts B emf between points A and B on the wire has magnitude 8 Volts C emf between points A and C on the wire has magnitude 16 Volts D none of these 1 m 1 1 0 0 B y x 1m

29 The needle of a deflection galvanometer shows a deflection of 60 due to a short bar magnet at a certain distance in tanA position If the distance is doubled then the deflection will be 2 13 1 tan 1 3 tan 3 3 2 tan 8 4 None of these

An electric potential difference will be induced 1 between the ends of the conductor shown in the diagram when the conductor moves in the direction 1 P 2 Q 3 L 4 M N P M dan fax i fund a ka 1 P 2 Q 3 L 4 M 1

A R L C circuit containing 520 resistor a 230 mH inductor and a 8 8 F capacitor is driven by an A C voltage source that has an amplitude of 150V and frequency v 80 Hz How much average power is dissipated by this circuit 1 Zero 3 39 3 W 2 78 6 W 4 19 6 W

Figure shows the top view of a rod that can slide without friction The resistor is 6 092 and a 2 5T uniform magnetic field is directed perpendicularly downward into paper If length of moving rod is 1 2m and it moves with a constant speed of 2 m s then the rate at which energy is delivered to the resistor is BOD l 1 12 W 3 3 W www R F 2 6 W 4 201 Ron

In the L R circuit shown in the figure the key K is closed at time t 0 L 00000000 R R 3 The current through R decreases with time t The drop across L increases with The magnetic energy stored in the steady state equals L E The total current through the battery is in the steady state E E

In the given figure shown below a conducting circular loop of radius I 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 1 Bol R x xAX X XXX RX XX xxx e X X X X X 2 Bol 2R

A B I The diagram shows a rectangular loop of wire moving away in the direction of the blue arrow from a long straight wire carrying a constant current I in the direction of the red arrow Which of the following describes the induced current in the resistor in the rectangular loop The induced current in the resistor is directed from B to A The induced current in the resistor is directed from A to B There is no induced current flowing through the resistor

Two parallel long resistanceless rails are joined at ends by a resistance R A slider with zero resistance of mass length has been imparted a velocity vo System is kept in horizontal plane submerged in a uniform magnetic field B B Q B m Vo The distance travelled by slider before it stops is mv R B The direction of current in slider is from P to Q The velocity of slider at time t The velocity of slider at time t mR Vo is B 2 mR Vo is

Figure shows an electrical circuit which has a rectangular region of uniform and constant magnetic field B A long metallic sheet of width is being moved with velocity v Reading of galvanometer G will be O O Zero Blv R R www D 714 xxx xx xxxxx V

1 The magnetic field between the poles of the electromagnet is uniform at any time but its magnitude is increasing at the rate of 0 01T s The area of the conducting loop in the field is 1m and the total circuit resistance including the meter is 1002 a Explain Faraday s law b Find the induced emf and the induced current in the circuit

conducting rod of length and mass m is released from rest at t 0 in magnetic field on parallel rails to move vertically downward due to gravity as shown in figure ark correct statement by assuming there is no dielectric breakdown XXX Velocity of rod at time t is equal to mgt B 1 C m Acceleration of rod keeps decreasing but velocity of rod keeps increasing Acceleration of rod keeps decreasing while velocity of rod increases till it attains terminal velocity Acceleration of rod is constant and velocity of rod keeps increasing

A rectangular loop of N closely packed turns is positioned near a long straight wire as shown in figure The rectangular loop performs linear SHM with its distance a varying as a a Asinot where A a or b The induced emf in the loop has the peak value A HoNi 2 C HoNi 2 l 1 A ao la Aw b b Aw B D lb ao a b lb 2T an H Ni 2 H Ni 3 Aw N tu

Problem 15 The electrical equivalent circuit of a crystal consists of a series L 1 H 90 C 0 01 pF R 1 k connected in parallel with capacitor C 10 pF Find the series and parallel resonant frequencies of the crystal Find Q at each frequency

A conducting ring of radius R is rolling without sliding on horizontal surface A uniform magnetic field B perpendicular to plane of the ring exist in the region Choose the correct option Toe B A 000 IV B IVc VBI IVc Vol IVA Vcl 2BwoR

Capacitor of capacitance Cis connected to parallel conducting rails A conducting rod of mass mand length connected to spring of spring constant k is placed on rails The whole arrangement is placed in magnetic field of magnitude Bo which is perpendicular to plane If spring is initially compressed by xo it takes B 1 C ak get back to initial position Find a m rooo k m time to

A capacitor of capacitance 2uF is firstly charge by connecting across a 200 V battery then it is allowed to get discharged through a resistor R The figure shows an experimental plot discharging of a capacitor The value of R is log 2 0 7 200V 100V 50V 25V 1 25 k 2 70 140 210 t ms 2 50 k

po The lower and upper half power 3 dB frequencies of an RC coup amplifier are 20 Hz and 20 kHz respectively Find the frequencies at which the level is 1 dB less than its mid frequency value

A series combination of resistor R and capacitor C is connected to an AC source of angular frequency Keeping the voltage same if the frequency is changed to c 3 the current becomes half of the original current Then the ratio of the capacitive reactance and resistance at the former frequency is AIIMS 2018 1 0 6 3 2 2 3 4 6

The network shown in figure is part of a complete circuit A www 192 15 V 5 mH vooooooo If at a certain instant the current is 5 A from A to B and is decreasing at a rate of 10 A s then VB VA equals 15 V B If at a certain instant the current is 5 A from A to B and is decreasing at a rate of 10 A s then VB VA equals 25 V If current is of 5 A from B to A and is decreasing at a rate of 10 A s then VB VA equals 15 V If current is of 5 A from B to A and is decreasing at a rate of 10 A s then VB VA equals 10V

Consider the shown network the capacitor C 6 30e F has an initial charge C C 4 F e 1 and R 80 Q Initially C is uncharged At t 0 the switch Sis closed The charge on C in C at t 192 s is x then value of S R 90 is

A rectangular loop of sides 20 cm 10 cm carrying I of 12 A is placed in different orientations as shown in the figures below If there is a uniform magnetic field of 0 3 T in the positive Z direction in which orientations the loop would be in 1 Stable equilibrium II unstable equilibrium I II a 1 ll Ob I Ill c II IV Od II III B N y III IV N 1 p

A toroid having a rectangular cross section a 2 00 cm by b 3 00 cm and inner radiu r 4 00 cm consists of 500 turns of wire that carries a current I Imax sin cot with Imax 50 0 A and 0 frequency f 60 0 Hz A coil that consists of 20 turns of wire links with the toroid as shown 2n in figure who time Toroid HAKI 5 B N 500 e pr C Maximum value of induced emf is 0 422 V D Maximum value of induced emf is 0 122 V N 20 time

A conducting loop is pulled with a constant velocity towards a region of uniform magnetic field B as shown in figure Then the current induced in the loop is d 2r X X X X X X XXX B X V X X X X X X X X X X d X X X X X X X X X X X X X X Clockwise while entering Anti clockwise while entering Zero when completely inside

This section contains 8 multiple choice questions Each question has 4 choices A B C and D for its answer out of which one or more than one is are com Consider the circuit as shown in diagram In steady state L 2mH 100 V 402 www 20 4 mH 4 Current through inductor L is 25 A Potential difference across L is zero Energy stored in inductor L is 1 25 J Current through L2 is zero

L R circuit is shown in figure just after the key K is closed mooooooo E R www K The current in the circuit is zero Potential drop across the resistor is zero EMF developed across the inductor equals the emf of the battery

O 11 40 17 5 A In the L R circuit the value of Lis T resistance Ris 30 Q If in the circuit an alternating em of 200 V at 50 cycles sec is connected the impedanc of circuit and current respectively will be O 30 7 0 6 5 A 40 4 0 5 A 0 4 500 40 H and value

A charge q having mass m enters a circular region of radius R having magnetic field B n RqB If the velocity of the particle is then m it passes through the centre of the circular region O Find n c de 9 yhh Avui yg qau a ude gem n RqB a m X ad uz za X X R 30 X x x X B

Consider the circuit as shown in diagram In steady state L ooooo 2 mH 100 V S 492 292 4 mH L Current through inductor L is 25 A Potential difference across L2 is zero Energy stored in inductor L2 is 1 25 J Current through L2 is zero

In a cylindrical region of radius R there exists a time dB varying magnetic field B such that k 0 A dt charged particle having charge q is placed at the point P at a distance d R from its centre O Now the particle is moved in the direction perpendicular to OP see figure by an external agent upto infinity so that there is no gain in kinetic energy of the charged particle Choose the correct statement s 1 2 4 X X X P X 9TR Work done by external agent is if d 2R 9 R 8 Work done by external agent is if d 4R Work done by external agent is 97R k 4 if d 4R Work done by external agent is if d 6R K