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iq Teereemnermonenessnoie poem, , _, , Two coils of self inductances 2 mH and 8 mH are, placed so close together that the effective flux in one, coil is completely linked with the other. The mutual, inductance between these coils is :, (1) 10 mH (2) 6 mH, , (3) 4 mH (4) 16 mH, , A metallic ring is dropped down, keeping its plane, perpendicular to a constant and horizontal magnetic, field. The ring enters the region of magnetic field, at t = 0 and completely emerges out at t = T sec., The current in the ring varies as:, ae a, , , , (3) at ,, , , , The primary and secondary coils of a transformer, have 50 and 1500 turns respectively. If the magnetic, flux @ linked with the primary coil is given by, = $+ 4t, where ¢ is in webers, t is time in seconds, and ¢y is a constant, the output voltage across the, , secondary coil is :, (1) 30 volts (2) 90 volts, (3) 120 volts (4) 220 volts, , A transformer is used to light a 100 W and 110V, lamp from a 220 V mains. If the main current is, 0.5 amp, the efficiency of the transformer is, approximately :, (1) 10% (2) 30%, , (3) 50% = (4) 90%, , 5., , A circular disc of radius 0.2 meter is placed in a, Z, , uniform magnetic field of 7 wh/m? in such way that, , its axis makes an angle of 60° with B . The magnetic, , flux linked with the disc is :(1) 0.08 wb (2) 0.01 wb, (3) 0.02 wo (4) 0.06 wb, , , , , , A long solenoid has 500 turns. When a current, of 2 ampere is passed through it, the resulting, magneticflux linked with each turn of the, solenoid is 4 x 10-4 wb, The self—inductance of, the solenoid is :(1) 1.0 henry, , (3) 2.5 henry, , (2) 4.0 henry, (4) 2.0 henry, , A rectangular, a square, a circular and an elliptical, loop, all in the (x - y) plane, are moving out of, a uniform magnetic field with a constant velocity,, V = vi. The magnetic field is directed along the, negative 2 axis direction. The induced emf, during, the passage of these loops, out of the fleKd region,, will not remain constant for , (1) any of the four loops, , (2) the rectangular, circular and elliptical loops, (3) the circular and the elliptical loops, , (4) only the elliptical loop, , 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 :, {(1).1.6 «pV (2.3.2 2 pV, , (3) 4.8 1 pV (4) 0.8 x pV, , , , AIPMT (Pre)'2010), , A conducting circular loop is placed in a uniform, magnetic field, B = .025 T with its plane, perpendicular to the loop. The radius of the loop, is made to shrink at a constant rate of, 1 mm s*. The induced e.m-f. when the radius is, 2 cm, is :, , (1) 2 pV (2) 2apV, , (3) mV @) Suv, , 139

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ALLER, GAINS 2010 AIPMT(Mains)/2012), , 10. A solenoid of radius R and length L has a current, I =I, coswt. The value of induced electric field at, a distance of r outside the solenoid, is :, , () Hane svn, , HonlyoR®, , r, , , , (2) sinet, , 2, (3) HetlR Snot, , (4) Zero, [AIPM T(Pre)/20120, , 11. A coil of resistance 4009 Is placed in a magnetic, , field. If the magnetic flux ¢[Wb) linked with the coil, varies with time t (sec) as, , o = 50t? + 4,, , The current in the coil at t = 2 sec is :, , (1) 2A {2) 1A, , (3) 0.54 (4) 0.1A, , 12. The current ()) in the inductance Is varying with time, , according to the plot shown in figure., , Which one of the following is the correct variation, of voltage with time in the coil ?, , “s Ys, , , , (1), , , , , , T/2, , , , , , , , 13. Ina coil of resistance 10 Q, the induced current, developed by changing magnetic flux through il,, is shown in figure as a function of time. The, magnitude of change in flux through the coil in, Weber is:, ifamp), 4, , 0,1 tis), , (1) 6 (2)4 (4) 2, GGEEEESEESENEET-UG!2013, , 14. A wire loop is rotated in magnetic field. The, , frequency of change of direction of the induced, emf. is =, , {1) Six times per revolution, (2) Once per revolution, (3) twice per revolution, (4) four times per revolution, , 15. A transformer having efficiency of 90% is working, on 200V and 3kW power supply. If the current, in the secondary coil is 6A, the voltage across the, secondary coil and the current in the primary coil, respectively are >, (1) 300 V, 154, (2) 450 V, 154, (3) 450V, 13.54, (4) 600, 154, , 16., , (3) 8, , The time constant of a circuit is 10 sec, when a, resistance of 10 is connected in series in a, previous circuit then time constant becomes 2, second, then the self inductance of the circuit is:() 25H (2) 5H, , (3)15H (4) 25H, , Ce), , MM rece muavinarwniwernenn sin neocons

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21. A copper disc of radius 10 cm Is rotating in, , magnetic field B = 0.4 gauss with 10 rev./sec, What, , 17. A conducting square frame of side ‘a’ and a long will, be ital difference across peripheral point:, straight wire carrying current I are located in the potential ierence a es poms, , , , , , of disc., same plane as shown In the figure. The frame, moves to the right with a constant velocity V'. The 1.20mi Feu AO RAY, emf induced in the frame will be proportional to: (3) zero (4) Sxuv, 22. A long solenoid has 1000 turns, When a current, I of 4A flows through it, the magnetic flux linked with, —Lsv each turn of the solenoid is 4 x10 Wb. The self, , inductance of the solenoid is :(1) 4H (2) 3H (3) 2H (4) 1H, , , , , , , , —a—>, , , , , , , , , , 1 1 23. Auniform magnetic field is restricted within a region, () Gyoar (2) Dxta of radius . The magnetic field changes with time, , 1 1 ata rate 1 Dopillof radius R > 1 enclosesthe, 3) (2x ~ aX2x+ a) (4) x cf, region rand loop 2 of radius R is outside the region, of magnetic field as shown in the figure below. Then, the e.m.f. generated is :, 18. An electron moves on a straight line path XY as, shown. The abcd Is a coil adjacent to the path of, electron. What will be the direction of current, if ee, any, induced in the coil ?, , (y) =P aR? in loop 1 and zero in lop 2, , , , , , , , , , , , , , , , , , ‘ é dB, (2) “a in loop 1 and zero in loop 2, c, Xr electron a (3) Zero in loop 1 and zero in loop 2, dB dB, (1) No current induced (4) a in loop 1 and ain loop 2, (2) abod, (3) adcb 24 ©B-2T, (4) The current will reverse its direction as the * = v= lene, electron goes past the coil imZs00, {LT, 19. A solenoid having 500 turns and length 2 m has A wire is sliding on two parallel conducting rails, , 3 radius of 2 cm, then self inductance of solenoid ? placed at a separation of 1m as shown in figure., ()4x104H (2)2 x10*H Magnetic field 2T exists in a directi tlcul, 8 x10CH () 16 x10°H to rails, What force is necessary to keep the wire, , 20. Find the dimensions of inductance :- moving with a constant velocity of 1 cm/sec?, 0) Mirra (2) MITA" (10.08 x10°N (2) Bx 10" N, (3) MLT*A7 (4) MLTA*, (3)4 x10°N (4) 8 x10*N, E

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_, A DC motor operates with 220V mains. Initially, , 25., , 27., , it draws current of 20A. The resistance of starter, is 62. When the motor runs at its full speed it, consumes 500 W power. Find the current drawn, by it., , , , , , , , , , (1) 5A (2) 10A {3) 154 (4) 204, |, I ft, +, >It, , Flux passing through loop is proportional to :(1) ocr (2) hoes (3) ect, (4) art, , A body enters in MRI machine in 10 sec. If the, magnetic field is 1,5 T and circumference of MRI, machine is 0.9 m then find out emf induced in the, , body., (1)0.96 V (2)9.6V (3) 9.6 mV (4)96mV, , A rod of length 50 cm moves with a speed of, 10 cm/s, in a uniform magnetic field of strength, 10 G at an angle of 30° with the field. The emf, induced accross the ends of the rod is :, (1) 5000 CGS unit (2) 2500 CGS unit, (3) 7500 CGS unit (4) 1000 CGS unit, , NEET(UG) 2017, , 29., , 30., , 142, , A long solenoid of diameter 0.1 m has 2 x 104, tums per meter. At the centre of the solenoid. a, coil of 100 turns and radius 0.01 m is placed with, its axis coinciding with the solenoid axis, The, current in the solenoid reduces at a constant rate, to OA from 4A in 0.05 s. If the resistance of the, coilis 10x22. the total charge flowing through the, coil during this time is :, {1) 16 pC (2) 32 pc, , (3) 16 « pC (4) 32 x pC, , Figure shows a circuit that contains three identical, resistors with resistance R = 9.0 Q each, two, identical inductors with inductance L = 2.0 mH, each, and an ideal battery with emf ¢ = 18 V. The, current ' through the battery just after the switch, closed is,...... >, , , , )02A, (3) 0 ampere, , (22A, (4) 2 mA, , , , A small piece of metal (1, = 20) of volume 10 cm?, has a uniform magnetic fiekl 4 T inside it. The, magnetic energy stored in the metal B Is :, (1) 3.18 J (2) 5.64 J, , (3) 6.36 J (4) 1.59 J, , A long solenoid of radius 2 cm has 100 tums/em, and caries a current of 5A. A coil of radius 1 an, having 100 turns and a total resistance of 20 Nis, , placed inside the solenoid co-axially. The coil is, connected to galvanometer, If current in the, solenoid is reversed in direction. Find the charge, , flown through the galvanometer., (1) 2x104C (2)1x107C, (3), 4 x10"°C (4)8 x10*C, , After how much time energy becomes x of the, , maximum value in a R-L circuit where R ~ 22 and, L = 2mH?, (1) 1 ms, , (2)0.5 ms (3)2ms (4) 1.5 ms, , NEET(UG) 2018), , 34,, , The magnetic potential energy stored In a certain, inductor is 25 mJ, when the current in the inductor, is 60 mA. This inductor is of inductance :, (1) 0.138 H (2) 138.88 H, (3) 1.389 H (4) 13.89 H, , 35., , Two long wires having current as shown placed at, seperation 2m. Magnetic field at mid point is:, Be?, S00A SO0A, ———, 2m, (1) 110° T (2) 2x10*T, (3) 2 x108 T (4)4x10°T, , FIR eecontemmn 3. «, , snecvomncsnns