Electromagnetic Induction PYQs Set 4 (PDF)

Set 4 of 10 · Questions 91-120 of 274

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Mere Teacher · Previous Year Questions NEET Physics · Electromagnetic Induction · Set 4 (Q91-120)
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91. $The magnetic flux linked with a coil varies as φ = 3 t^{2} + 4 t + 9 . The magnitude of the emf induced at t = 2 seconds is$ (1) $8 V$ (2) $16 V$ (3) $32 V$ (4) $64 V$ 92. $A conducting circular loop made a thin wire, has area 3.5 \times 10^{- 3} m^{2} and resistance 10Ω. It is placed perpendicular to a time dependent magnetic field B (t) = (0.4 T) sin (50 πt) . The field is uniform in space. Then the net charge flowing through the loop during t = 0 s and t = 10 ms is close to:$ (1) $14 mC$ (2) $7 mC$ (3) $0.14 mC$ (4) $6 mC$ 93. $A copper disc of radius 0.1 m rotates about an axis passing through its centre and perpendicular to its plane with 10 revolutions per second in a uniform transverse magnetic field of 0.1 T . The emf induced across the radius of the disc is$ (1) $\frac{π}{10} V$ (2) $\frac{2 π}{10} V$ (3) $10 πmV$ (4) $20 πmV$ 94. $The self inductance ' L' of a solenoid of length ' l' and area of cross-section ' A' with a fixed number of turns ' N, increases as$ (1) $l decreases and A increases$ (2) $both l and A decrease$ (3) $both l and A increase$ (4) $l increases and A decreases.$ 95. $In an ac circuit an alternating voltage 2002 sin 100 t volts is connected to a capacitor of capacity 1 μF . The r.m.s. value of the current in the circuit is$ (1) $10 mA$ (2) $100 mA$ (3) $200 mA$ (4) $20 mA$ 96. $A long solenoid of diameter 0.1 m has 2 \times 1 0^{4} turns per meter. At the centre of the solenoid, a coil of 100 turns and radius 0.01 m is placed with its axis coinciding with the solenoid axis. The current in the solenoid reduces at a constant rate to 0 A from 4 A in 0.05 s . Ifthe resistance ofthe coil is 10 π^{2} Ω, the total charge flowing through the coil during this time is$ (1) $16 μC$ (2) $32 μC$ (3) $16 πμC$ (4) $32 πμC$ 97. $How many meters of a thin wire are required to design a solenoid of length 1m and L = 1mH? Assume cross-sectional diameter is very small-$ (1) $10 m$ (2) $40 m$ (3) $70 m$ (4) $100 m$ 98. $Power dissipated in an LCR series circuit connected to an A.C. source of emf ϵ is$ (1) $\frac{ϵ ^{2} R ^{2} + ( Lω - \frac{1}{Cω} ) ^{2}}{R}$ (2) $\frac{ϵ ^{2} [ R ^{2} + ( Lω - \frac{1}{Cω} ) ^{2}}{R}$ (3) $\frac{ϵ ^{2} R}{R ^{2} + ( Lω - \frac{1}{Cω} ) ^{2}}$ (4) $\frac{ϵ ^{2} R}{[ R ^{2} + ( Lω - \frac{1}{Cω} ) ^{2}}$ 99. $The core of a transformer is laminated because$ (1) $ratio of voltage in primary and secondary may be increased$ (2) $energy losses due to eddy currents may be minimized$ (3) $the weight of the transformer may be reduced$ (4) $rusting of the core may be prevented.$ 100. $The mutual inductance (M) of the two coils is 3 H, The self inductances of the coils are 4 H and 9 H respectively. The coefficient of coupling between the coils is$ (1) $0.3$ (2) $0.4$ (3) $0.5$ (4) $0.6$ 101. $An series L - C - R circuit is connected to a source of A . C . current. At resonance, the phase difference between the applied voltage and the current in the circuit, is$ (1) $π$ (2) $zero$ (3) $π /4$ (4) $π /2$ 102. $A coil of 40 henry inductance is connected in series with a resistance of 8 ohm and the combination is joined to the terminals of a 2 volt battery. The time constant of the circuit is$ (1) $5 seconds$ (2) $1/5 seconds$ (3) $40 seconds$ (4) $20 seconds.$ 103. $The potential differences across the resistance, capacitance and inductance are 80 V, 40 V and 100 V respectively in an L - C - R circuit. The power factor of this circuit is$ (1) $0.4$ (2) $0.5$ (3) $0.8$ (4) $1.0$ 104. $An infinitely long cylinder is kept parallel to a uniform magnetic field B directed along positive z -axis. The direction of induced current on the surface of cylinder as seen from the z -axis will be$ (1) $clockwise of the +ve z -axis$ (2) $anticlockwise of the +ve z -axis$ (3) $zero$ (4) $along the magnetic field$ 105. $If N is the number of turns in a coil, the value of self inductance varies as$ (1) $N^{0}$ (2) $N$ (3) $N^{2}$ (4) $N^{- 2}$ 106. $Regarding self-inductance: (A) The self-inductance of the coil depends on its geometry. (B) Self-inductance does not depend on the permeability of the medium. (C) Self-induced e.m.f. opposes any change in the current in a circuit. (D) Self-inductance is electromagnetic analogue of mass in mechanics. (E) Work needs to be done against self-induced e.m.f. in establishing the current. Choose the correct answer from the options given below:$ (1) $A, B, C, E only$ (2) $B, C, D, E only$ (3) $A, C, D, E only$ (4) $A, B, C, D only$ 107. $A fully charged capacitor C with initial charge q_{0} is connected to a coil of self inductance L at t = 0. The time at which the energy is stored equally between the electric and the magnetic fields is:$ (1) $π LC$ (2) $\frac{π}{4} LC$ (3) $2 π LC$ (4) $LC$ 108. $A circuit when connected to an AC source of 12 V gives a current of 0.2 A . The same circuit when connected to a DC source of 12 V, gives a current of 0.4 A. The circuit is$ (1) $series LR$ (2) $series RC$ (3) $series LC$ (4) $series LCR$ 109. $A 100 millihenry coil carries a current of 1A. Energy stored in its magnetic field is$ (1) $0.5 J$ (2) $1 J$ (3) $0.05 J$ (4) $0.1 J$ 110. $A solenoid of inductance 2 H carries a current of 1 A . What is the magnetic energy stored in a solenoid?$ (1) $4 J$ (2) $2 J$ (3) $5 J$ (4) $1 J$ 111. $A conducting circular loop of area 1.0 m^{2} is placed perpendicular to a magnetic field which varies as B = sin (100 t) Tesla. If the resistance of the loop is 100Ω, then the average thermal energy dissipated in the loop in one period is____J.$ (1) $π^{2}$ (2) $π$ (3) $\frac{π}{2}$ (4) $2 π$ 112. $A sheet is placed in a horizontal surface in front of a strong magnetic pole. A force is needed to(A) hold the sheet there, if it is magnetic.(B) hold the sheet there, if it is non-magnetic.(C) move the sheet away from the pole with uniform velocity, if it is conducting.(D) move the sheet away from the pole with uniform velocity, if it is both non-conducting and non-polar.Choose the correct statement(s) from the options given below. [NEET 2024]$ (1) $B and D only$ (2) $A and C only$ (3) $A, C and D only$ (4) $C only$ 113. $A step‐up transformer operates on a 230 V line and supplies a load of 2 ampere. The ratio of the primary and secondary windings is 1 : 25 . The current in the primary is$ (1) $15 A$ (2) $50 A$ (3) $25 A$ (4) $12.5 A$ 114. $For a coil having L = 2 mH, current flow through it is I = t^{2} e^{- t} then, the time at which emfbecomes zero$ (1) $2 sec$ (2) $1 sec$ (3) $4 sec$ (4) $3 sec .$ 115. $An ac voltage is applied to a resistance R and an inductor L in series. If R and the inductive reactance are both equal to 3Ω, the phase difference between the applied voltage and the current in the circuit is$ (1) $π /6$ (2) $π /4$ (3) $π /2$ (4) $zero$ 116. $A jet plane of wing span 20 m is travelling towards west at a speed of 400 m s^{- 1} . If the earth's total magnetic field is 4 \times 10^{- 4} T and the dip angle is 30^{\circ}, at that place, the voltage difference developed across the ends of the wing is$ (1) $3.2 V$ (2) $6.4 V$ (3) $1.6 V$ (4) $0.8 V$ 117. $A conducting circular loop is placed in a uniform magnetic field 0.04 T with its plane perpendicular to the magnetic field. The radius of the loop starts shrinking at 2 mm / s . The induced emf in the loop when the radius is 2 cm is$ (1) $4.8 πμV$ (2) $0.8 πμV$ (3) $1.6 πμV$ (4) $3.4 πμV$ 118. $A conducting loop of radius \frac{10}{π} cm is placed perpendicular to a uniform magnetic field of 0.5T. The magnetic field is decreased to zero in 0.5 s at a steady rate. The induced emf in the circular loop at 0.25 s is:$ (1) $emf = 1 mV$ (2) $emf = 10 mV$ (3) $emf = 100 mV$ (4) $emf = 5 mV$ 119. $A rectangular, a square, a circular and an elliptical loop, all in the (x - y) plane, are moving out of a uniform magnetic field with a constant velocity, V = v i . The magnetic field is directed along the negative z axis direction. The induced emf, during the passage of these loops, out of the field region, will not remain constant for$ (1) $the circular and the elliptical loops$ (2) $only the elliptical loop$ (3) $any of the four loops$ (4) $the rectangular, circular and elliptical loops$ 120. $A magnetic field of flux density 1.0 Wb m^{- 2} acts normal to a 80 turn coil of 0.01 m^{2} area. If this coil is removed from the field in 0.2 second, the emf induced in it is$ (1) $0.8 V$ (2) $4 V$ (3) $5 V$ (4) $8 V$