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DEPARTMENT OF PHYSICS, , Physics, , , , Time : 1.00 hr xi Marks : 20, , , , , , E.m, Induction And A.c. Current |, , , , , , 1) The magnetic flux passing perpendicular to the plane of the coil and directed into the paper is, varying according to relation ¢ = 612 — 71+ 1, where ¢ is in milli-weber and t is in sec. The, magnitude of e.m.f. induced in the loop when t = 2s is :, , A)- 31 mv B) +31 mv C)-15mVv D) +15 mv, , 2) Acoil of 50 turns has dimensions 10 « 10 cm. Itis rotated at the rate of 5 r.p.s. in a uniform, magnetic field of flux density 0.7 T. The max. e.m.f. induced in it is :, , A) 8V B) 11V C) 15V D) 19V, , 3) A thin circular ring of area A is perpendicular to uniform magentic field of induction B. A, small cut is made in the ring and a galvanometer is connected across the ends such that the, total resistance of circuit is R. When the ring is suddenly squeezed to zero area, the charge, flowing through galvanometer Is :, , a) Se 8) AS c) ABR p) BA, , 4) A solenoid having a core of 10~°m’* in cross-section, half air (4. = 1) and half iron {4.. = 500), is 1 m long, the no. of turns are 2000. What is coefficient of self induction ?, , ww, 2m—», , , , A)O.S5H B)0.75H C)1.26H D) 2.25 H., 5) A toroid is along coil of wire, wound over a circular core. The coefficient of self inductane of, the toroid is given by (radius=r), when mag. field is within it is uniform and R >> r:, ltipNr* MgNr oN? HoN?1?, 2k 2R R 2R, , 6) The voltage of A.C. source varies with time according to equation V = 120 sin 100 nt cos 100, mt. Then frequency of source is :, , A)L=, , , , By =, , , , cyL= D)L=, , , , A) 50 Hz B) 100 Hz C) 150 Hz D) 200 Hz., , 7) In house having a 220 V line, there are (a) 60 W bulb (b) 1000 W heater (c) 40 watt radio. What, is current passing through fuse for this line :, , A)1A B)2A Caan D)5A., , 8) Acircuit contains two inductors of self inductance L, and |» in series. If Mis the mutual, inductance then the effective inductance of the circuit shown will be :

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A) Ly +e B) L, +1>- 2M C)l,;+lo+M D) L, + Ls +2M, , 9) The equivalent inductance of two inductors is 2.4 H when connected in parallel and 10 H when, connected in series, then the individual inductance is, , A) 6H,4H B) SH,5H C) 7H, 3H D) 8H,2H., , 10) On a cylindrical rod two coils are wound one above the other then the coefficient of mutual, induction if the inductance of each coil is 0.1 H, will be, , A)O.4H B)0.3H c)0.2H D) 0.1 H., 11) In series resonant LCR ckt, the voltmeter and ammeter readings are :, - “>, , bee ae pe, , , , , , , , — n+, nwa c, , (A), , , , A) V=100V,1=2A B)V=100V,1=5A, C) V=100V,1=2A D) V=300V,1=1A, , 12) The flux linked with a circuit is given by ¢ = 1 — 31—7 . The graph between time (x-axis) and, induced emf. (y-axis) will be, , A) Straight line through the origin B) Straight line with negative intercept, , C) Parabola through the origin D) Parabola not through the origin., , 13) A coil having 500 square loops each of side 10 cm is placed normal to a magnetic flux which, increases at the rate of 1.0 tesla/second. The induced e.m.f. in volts is :, , A) 0.1 B) 0.5 c)1 D)5., , 14) A rectangular coil of 20 turns and area of cross-section 25 sqcm has a resistance of 100 ohm., If a magnetic field which is perpendicular to the plane of the coil changes at the rate of 1000, tesla per second, the current in the coil is :, , A) 1.04 B)50A C)O5A D) 5.0 A.

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15) A coil has an area of 0.05m? and it has 800 turns. It is placed perpendicularly in a magnetic, field of strength 4 x 10-° Wb/m®, itis rotated through 90° in 0.1s. The average e.m.f. induced, in the coil is :, , A) 0.056 V B) 0.046 V C) 0.026 V D) 0.016 V., , 16) An aluminium ring B faces an electromagnet A. The current | through A can be altered, 6, A, , , , , , , , ¢ Til, , Observer “1 A, , , , , , , , side, , A) Where | increases or decreases, B will not experience any force, B) If | decreases, A will repel B, C) If lincreases, A will attract B, , D) If | increases, A will repel B., , 17) Two rails of a railway track insulated from each other and the ground are connected to a milli, voltmeter. What Is the reading of voltmeter, when a train travels with a speed of 180 km/h, along the track. Given that the vertical component of earths magnetic field is, 0.2 x 10°-¢weber/m* and the rails are separated by 1 metre, , A) 10-2 volt B) 10~ volt C) 10°? volt D) 1 volt., , 18) An aeroplane in which the distance between the tips of wings is 50 m is flying horizontally, with a speed of 360 km/h over a place where the vertical components of earth magnetic field, is 2.0 x 10-*weber/m? . The potential difference between the tips of wings would be :, , A)O.1V B) 1.0V cjo2Vv D) 0.01 Vv., , 19) A metal conductor of length 1 m rotates vertically about one of its ends at angular velocity 5, rad per second. If the horizontal component of earths magnetic field is 0.2 x 10° T, then the, e.m.f. developed between the two ends of the conductor is :, , A) Smv B)5x10*V C) 50 mv D) 50 nV, , 20) A conducting wire is moving towards right in a magnetic field B. The direction of induced, current in the wire is shown in the figure. The direction of magnetic field will be :

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A) In the plane of paper pointing towards right, B) In the plane of paper pointing towards left, C) Perpendicular to the plane of paper and down-wards, , D) Perpendicular to the plane of paper and upwards.