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Magnetic Flux, 1., , A circular disc of radius 0.2 meter is placed in a, uniform magnetic field of induction {>} in, m, , such a way that its axis makes an angle of 60° with, B. The magnetic flux linked with the disc is, , (a) 0.08 Wb (b) 0.01 Wb, (c) 0.02 Wb (d) 0.06 Wb (2008), Faraday’s Law of Induction, , 2. A 800 turn coil of effective area 0.05 m?, , is kept perpendicular to a magnetic field, 5 x 10° T. When the plane of the coil is rotated by, 90° around any of its coplanar axis in 0.1 s, the emf, induced in the coil will be, , (a) 0.02 V (b) 2V, , (c) 0.2V (d) 2x 10°V, (NEET 2019), , A uniform magnetic field is restricted within a, , region of radius r. The magnetic field changes with, time at a rate <. Loop | of radius R > r encloses the, t, , region r and loop 2 of radius R is outside the region, of magnetic field as shown in the figure. Then the, e.m.f. generated is, , @G, , (a) zero in loop 1 and zero in loop 2, , (o) 48 9,7 in loop 1 and - 22 g,?in loop 2, dt dt, , (c) ~ xR? in loop 1 and zero in loop 2, , (d) - 7 in oop 1 and zero in loop 2, (NEET-II 2016)

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A coil of resistance 400 Q is placed in a magnetic, field. If the magnetic flux $ (Wb) linked with the, coil varies with time ¢ (sec) as = 50f + 4. The, current in the coil at t = 2 sec is, , (a) OSA (b) 0.1 A, (c) 2A (d) 1A (2012), , A conducting circular loop is placed in a uniform, , etic field, B = 0.025 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 emf when the radius is 2 cm, is, , (a) 2npV (b) mpV, (c) uv (d) 2nV (2010), , 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=v?. The magnetic field is directed along the, , negative z axis direction. The induced emf, during, , the passage of these loops, out of the field region,, , will not remain constant for, , (a) the circular and the elliptical loops, , (b) only the elliptical loop, , (c) any of the four loops, , (d) the rectangular, circular and elliptical loops, (2009), , 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, , (a) 4.87 pV (b) 0.82 pV, (c) 1.6n pV (d) 3.40 pV (2009), Asa result of change in the magnetic, , flux linked to the closed loop as, shown in the figure, an e.m.f. V volt is, induced in the loop. The work done, (joule) in taking a charge Q coulomb, once along the loop is

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(a) QV (b) 2QV, (ce) QV/2 (d) zero. (2005), , 9. A rectangular coil of 20 turns and area of, cross-section 25 sq. cm has a resistance of 100 Q. If, a magnetic field which is perpendicular to the plane, of coil changes at a rate of 1000 tesla per second, the, current in the coil is, (a) LA (b) 50A, (c) OSA (d) 5A (1992), 10. A magnetic field of 2 x 107 T acts at right angles to, a coil of area 100 cm’, with 50 turns. The average, em. induced in the coil is 0.1 V, when it isremoved, from the field in t sec. The value of t is, (a) 10s (b) 0.1s, (c) 0.01 s (d) 1s (1991), , Lenz's Law and Conservation of Energy, , Ll. 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, any, induced in the coil?, , a, , b d, €, , jevesesenstaines® Sie enpads cata cneeeennnnne, x electron Y, , (a) The current will reverse its direction as the, , electron goes past the coil, (b) No current induced, (c) abed (d) adcb (2015), , 12. A metal ring is held horizontally and bar magnet, is dropped through the ring with its length along, the axis of the ring. The acceleration of the falling, , magnet is, , (a) more than g (b) equal tog, , (c) less than g (d) either(a) or (c) (1996), 13. Paraday’s laws are consequence of conservation of, , (a) energy, , (b) energy and magnetic field, , (c) charge, , (d) magnetic field (1991), Motional Electromotive Force, , 14. Acycle wheel of radius 0.5 m is rotated with constant, angular velocity of 10 rad/s in a region of magnetic, field of 0.1 T which is perpendicular to the plane, of the wheel. The EMF generated between its centre, and the rim is, (a) 0.25V (b) 0.125 V, , (c) 0.5 V (d) zero, (Odisha NEET 2019)

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a, , 15. A conducting square frame of side ‘a’ and a long, straight wire carrying current J are located in the, same plane as shown in the figure. The frame moves, to the right with a constant velocity ‘V. The emf, induced in the frame will be proportional to, , , , , , , , , , , , , , ) _, (2x+ay?’ :, l im>v, (b) (2x-a)(2x+a) :, —i—, 1 1, od d iz, O72 © oa, (2015 Cancelled), , 16. A thin semicircular conducting ring (PQR) of radius, r is falling with its plane vertical in a horizontal, magnetic field B, as shown in the figure., , The potential difference x *« *« «, developed across the ringwhen , 2, ® ,, its speed is v, is ;, , (a) zero « x dx Os, , (b) pew and Pis at higher potential, (c) mrBv and R is at higher potential, (d) 2rBy and Ris at higher potential (2014), , 17. A straight line conductor of length 0.4 m is moved, with a speed of 7 m/s perpendicular to a magnetic, field of intensity 0.9 Wb/m*. The induced e.m.f., across the conductor is, , (a) 5.04 V (b) 25.2V, (c) 1.26V (d) 2.52 V (1995), Energy Consideration : A Quantitative, Study, , 18. A long solenoid of diameter 0.1 m has 2 x 10* turns, 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 0 A from, 4 A in 0.05 s. If the resistance of the coil is 10 x? Q,, the total charge flowing through the coil during this, , time is, (a) 164C (b) 32C, (c) 16m pC (d) 32nyC (NEET 2017), , 19. In a coil of resistance 10 Q, the amp), induced current developed 4, by changing magnetic flux, through it, is shown in figure as a, function of time. The magnitude 6] Ol As), of change in flux through the coil, in weber is

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(a) 8 (b) 2 (c) 6 (d) 4, (Mains 2012), , 20. The magnetic flux through a circuit of resistance, R changes by an amount A@ in a time At. Then the, total quantity of electric charge Q that passes any, point in the circuit during the time Af is represented, by, , alt =, {a) Q RM (b) Q= R, ot i, {c) Q a“ (d) Gah (2004), , 21. The total charge, induced in a conducting loop when, it is moved in magnetic field depends on, (a) the rate of change of magnetic flux, (b) initial magnetic flux only, (c) the total change in magnetic flux, (d) final magnetic flux only. (1992), , EBD Eddy Currents, , 22. In which of the following devices, the eddy current, , effect is not used?, , (a) electric heater, , (b) induction furnace, , (c) magnetic braking in train, , (d) electromagnet (NEET 2019), Eddy currents are produced when, , (a) a metal is kept in varying magnetic field, , (b) a metal is kept in steady magnetic field, , (c) a circular coil is placed in a magnetic field, , (d) current is passed through a circular coil (1988), , ® Inductance, , 24., , 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, , (a) 0.138 H (b) 138.88 H, , (c) 1.389H (d) 13.89H (NEET 2018), , Acurrent of 2.5 A flows through a coil of inductance, 5 H. The magnetic flux linked with the coil is, , (a) 0.5 Wb (b) 12.5 Wb, , (c) zero (d) 2Wb, (Karnataka NEET 2013), , The current (J) 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 ? =i Tr, , Vv ul, () ih a ), Tz T ta T, —