Electromagnetic Induction PYQs Set 3 (PDF)

Set 3 of 10 · Questions 61-90 of 274

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Mere Teacher · Previous Year Questions NEET Physics · Electromagnetic Induction · Set 3 (Q61-90)
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61. $A conducting wire of length 2500 m is kept in east-west direction, at a height of 10 m from the ground. If it falls freely on the ground then the current induced in the wire is (Resistance of wire = 252 Ω, acceleration due to gravity g = 10 m / s^{2}, B_{H} = 2 \times 10^{- 5} T)$ (1) $0.2 A$ (2) $0.02 A$ (3) $0.01 A$ (4) $2 A$ 62. $A big circular coil of 1000 turns and average radius 10 m is rotating about its horizontal diameter at 2 rad s^{- 1} . If the vertical component of earth's magnetic field at that place is 2 \times 10^{- 5} T and electrical resistance of the coil is 12.56Ω, then the maximum induced current in the coil will be [NEET 2022]$ (1) $0.25 A$ (2) $1.5 A$ (3) $1 A$ (4) $2 A$ 63. $A magnetic field of 2 \times 1 0^{- 2} T acts at right angles to a coil of area 100 c m^{2}, with 50 turns. The average e.m.f. induced in the coil is 0. 1 V, when it is removed from the field in t sec. The value of t is$ (1) $10 s$ (2) $0.1 s$ (3) $0.01 s$ (4) $1 s$ 64. $The magnetic flux near the axis and inside the air core solenoid of length 60 cm carrying current I is 1.57 \times 10^{- 6} Wb . Its magnetic moment will be (cross-sectional area of a solenoid is very small as compared to its length, μ_{0} = 4 π \times 10^{- 7} SI unit)$ (1) $0.25 A$ (2) $0.50 A$ (3) $0.75 A$ (4) $1 A$ 65. $An inductor 20 mH, a capacitor 50 μF and a resistor 40 Ω are connected in series across a source of emf V = 10 sin 340 t . The power loss in A.C. circuit is$ (1) $0.76 W$ (2) $0.89 W$ (3) $0.51 W$ (4) $0.67 W$ 66. $The total charge, induced in a conducting loop when it is moved in magnetic field depends on$ (1) $the rate of change of magnetic flux$ (2) $initial magnetic flux only$ (3) $the total change in magnetic flux$ (4) $final magnetic flux only$ 67. $The expression for the magnetic energy stored in a solenoid of length L, in terms of magnetic field B and area A is$ (1) $\frac{1}{2 μ _{0}} B^{2} AL$ (2) $\frac{1}{2 ϵ _{0}} B^{2} AL$ (3) $\frac{1}{2 μ _{0}} BA^{2} L$ (4) $\frac{1}{2 ϵ _{0}} B A^{2} L$ 68. $A long solenoid of radius R carries a time (t) - dependent current I (t) = I_{0} t (1 - t) . A ring of radius 2 R is placed coaxially near its middle. During the time interval 0 \leq t \leq 1, the induced current (I_{R}) and the induced EMF (V_{R}) in the ring change as:$ (1) $Direction of I_{R} remains unchanged and V_{R} is zero at t=0.25$ (2) $At t=0.5 direction of I_{R} reverses and V_{R} is zero$ (3) $At t=0.25 direction of I_{R} reverses and V_{R} is maximum$ (4) $Direction of I_{R} remains unchanged and V_{R} is maximum at t=0.5$ 69. $A magnetic field of 2 \times 10^{- 2} T acts right angles to a coil of area 100 cm^{2} with 50 turns. The average e.m.f. induced in the coil is 0.1 V, when it is removed from the field in time ' t' The value of ' t' is$ (1) $2 \times 10^{- 3} s$ (2) $0.5 s$ (3) $0.1 s$ (4) $1 s$ 70. $Two coils have a mutual inductance 0.005 H. The current changes in the first coil according to equation I = I_{0} sinωt, where I_{0} = 10 A and ω = 100 π rad / sec . The maximum value of e.m.f. in the second coil is$ (1) $π$ (2) $5 π$ (3) $2 π$ (4) $4 π$ 71. $A long solenoid has 20 turns per cm . A small loop of area \frac{4}{π} cm^{2} is placed inside the solenoid normal to its axis. If the current carried by the solenoid changes steadily from 1.0 A to 3.0 A in 0.2 s, what is the magnitude of the induced emf in the loop while the current is changing?$ (1) $2.4 μV$ (2) $3.2 μV$ (3) $7.2 μV$ (4) $4.8 μV$ 72. $The source of time varying magnetic field may be (A) a permanent magnet (B) an electric field changing linearly with time (C) direct current (D) a decelerating charge particle (E) an antenna fed with a digital signal Choose the correct answer from the options given below.$ (1) $(C) and (E) only$ (2) $(D) only$ (3) $(A) only$ (4) $(B) and (D) only$ 73. $What is the self‐inductance of a coil which produces 5 V when the current changes from 3 ampere to 2 ampere in one millisecond?$ (1) $5000 henry$ (2) $5 milli‐henry$ (3) $50 henry$ (4) $5 henry$ 74. $A wheel with 20 metallic spokes each 1 m long is rotated with a speed of 120 rpm in a plane perpendicular to a magnetic field of 0.4 G. The induced emf between the axle and rim of the wheel will be (1 G = 10^{- 4} T) [NEET 2020]$ (1) $2.51 \times 10^{- 4} V$ (2) $2.51 \times 10^{- 5} V$ (3) $4.0 \times 10^{- 5} V$ (4) $2.51 V$ 75. $A 800 turn coil of effective area 0.05 m^{2} is kept perpendicular to a magnetic field 5 \times 1 0^{- 5} T . When the plane of the coil is rotated by 9 0^{o} around any of its coplanar axis in 0.1 s, the self-induced in the coil will be$ (1) $0.02 V$ (2) $2 V$ (3) $0.2 V$ (4) $2 \times 1 0^{- 3} V$ 76. $Consider a circular coil of wire carrying constant current I, forming a magnetic dipole. The magnetic flux through an infinite plane that contains the circular coil and excluding the circular coil area is given by φ_{i} . The magnetic flux through the area of the circular coil area is given by φ_{0} . Which of the following option is correct?$ (1) $φ_{i} > φ_{0}$ (2) $φ_{i} < φ_{0}$ (3) $φ_{i} = - φ_{0}$ (4) $φ_{i} = φ_{0}$ 77. $The magnetic flux through a coil perpendicular to its plane is varying according to the relation φ = 5 t^{3} + 4 t^{2} + 2 t - 5 Weber. If the resistant of the coil is 5 ohm, then the induced current through the coil at t = 2 sec will be:$ (1) $15.6 A$ (2) $16.6 A$ (3) $17.6 A$ (4) $18.6 A$ 78. $If current ' T' is flowing in the closed circuit with collective resistance ' R', the rate of production of heat energy in the loop as we pull it along with a constant speed ' V' is (L = length of conductor; B = magnetic field)$ (1) $\frac{BLV}{R}$ (2) $\frac{B ^{2} L ^{2} V ^{2}}{R ^{2}}$ (3) $\frac{BLV}{R ^{2}}$ (4) $\frac{B ^{2} L ^{2} V ^{2}}{R}$ 79. $The magnetic potential energy stored in a certain inductor is 25 mJ, when the current in the inductor is 60 mA. This inductor is of inductance [NEET 2018]$ (1) $1.389 H$ (2) $138.88 H$ (3) $0.138 H$ (4) $13.89 H$ 80. $An aeroplane is travelling horizontally towards west with a speed of 540 kmh^{- 1} . The wing span of the plane is 20 m . If the horizontal component of the earth's magnetic field at the location is 2.5 3 \times 10^{- 4} T and the dip angle is 30^{\circ}, the potential difference developed between the ends of the wing is$ (1) $1 V$ (2) $1.5 V$ (3) $0.75 V$ (4) $0.5 V$ 81. $In a pair of adjacent coils if the current in one coil changes from 10 A to 2 A in a time 0.2 s, an emf of 120 V is induced in another coil. The mutual inductance of the pair of the coils is$ (1) $2 H$ (2) $3 H$ (3) $6 H$ (4) $9 H$ 82. $Assertion (A): It is more difficult to push a magnet into a coil with more number of turns. Reason (R): The emf induced in a coil opposes the motion of a magnet when it is moved towards the coil.$ (1) $A is false, R is true$ (2) $Both A and R are true. R is correct explanation of A$ (3) $A is true, R is false$ (4) $Both A and R are true. R is not correct explanation of$ 83. $A circular coil has 100 turns, radius 3 cm and resistance 4Ω . The coil is co-axial with a solenoid of 200 turns / cm and diameter 4 cm . If the solenoid current is decreased from 2 A to zero in 0.04 s, then the current induced in the coil is$ (1) $4 π^{2} mA$ (2) $8 πmA$ (3) $30.3 mA$ (4) $45.5 mA$ 84. $Two coils ‘P’ and ‘Q’ are separated by some distance. When a current of 3A flows through coil 'P', a magnetic flux of 10^{- 3} Wb passes through 'Q'. No current is passed through 'Q'. When no current passes through 'P' and a current of 2A passes through 'Q', the flux through 'P' is?$ (1) $6.67 \times 10^{- 4} Wb$ (2) $3.67 \times 10^{- 3} Wb$ (3) $6.67 \times 10^{- 3} Wb$ (4) $3.67 \times 10^{- 4} Wb$ 85. $The magnetic flux through a loop of resistance 10Ω is varying according to the relation φ = 6 t^{2} + 7 t + 1, where φ is in milliweber, time is in second then at time t = 1 s the induced e.m.f. is$ (1) $12 mV$ (2) $7 mV$ (3) $19 mV$ (4) $19 V$ 86. $Physically, the self-inductance plays the role of$ (1) $inertia$ (2) $kinetic energy$ (3) $potential energy$ (4) $velocity$ 87. $The coefficient of mutual inductance between the primary and the secondary coil of a transformer is 0.2 H . When the current in the primary changes by 5 As^{- 1}, then the induced emf in the secondary will be$ (1) $5 V$ (2) $1 V$ (3) $25 V$ (4) $10 V$ 88. $The self induced emf of a coil is 25 volts. When the current in it is changed at uniform rate from 10 A to 25 A is 1s, the change in the energy of the inductance is:$ (1) $740 J$ (2) $437.5 J$ (3) $540 J$ (4) $637.5 J$ 89. $Two coils of self inductance 2 mH and 8 mH are placed so close together that the effective flux in one coil is completely linked with the other. The mutual inductance between these coils is$ (1) $16 mH$ (2) $10 mH$ (3) $6 mH$ (4) $4 mH$ 90. $A coil of resistance 50Ω is connected across a 5.0 V battery. If the current in the coil is found to be 50 mA after time t = 0.1 s battery is connected, then the inductance of the coil is$ (1) $\frac{5}{ln ( 2 )}$ (2) $10 ln (2)$ (3) $5 e^{4}$ (4) $\frac{10}{e ^{4}}$