Electromagnetic Induction PYQs Set 5 (PDF)

Set 5 of 11 · Questions 121-150 of 319

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Mere Teacher · Previous Year Questions JEE Main Physics · Electromagnetic Induction · Set 5 (Q121-150)
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121. $A fully charged capacitor C with initial charge q_{0} is connected to a coil of self inductance L at t = 0. The time at which the energy is stored equally between the electric and the magnetic fields is:$ (1) $π LC$ (2) $\frac{π}{4} LC$ (3) $2 π LC$ (4) $LC$ 122. $A circuit when connected to an AC source of 12 V gives a current of 0.2 A . The same circuit when connected to a DC source of 12 V, gives a current of 0.4 A. The circuit is$ (1) $series LR$ (2) $series RC$ (3) $series LC$ (4) $series LCR$ 123. $A 100 millihenry coil carries a current of 1A. Energy stored in its magnetic field is$ (1) $0.5 J$ (2) $1 J$ (3) $0.05 J$ (4) $0.1 J$ 124. $A solenoid of inductance 2 H carries a current of 1 A . What is the magnetic energy stored in a solenoid?$ (1) $4 J$ (2) $2 J$ (3) $5 J$ (4) $1 J$ 125. $A conducting circular loop of area 1.0 m^{2} is placed perpendicular to a magnetic field which varies as B = sin (100 t) Tesla. If the resistance of the loop is 100Ω, then the average thermal energy dissipated in the loop in one period is____J.$ (1) $π^{2}$ (2) $π$ (3) $\frac{π}{2}$ (4) $2 π$ 126. $A sheet is placed in a horizontal surface in front of a strong magnetic pole. A force is needed to(A) hold the sheet there, if it is magnetic.(B) hold the sheet there, if it is non-magnetic.(C) move the sheet away from the pole with uniform velocity, if it is conducting.(D) move the sheet away from the pole with uniform velocity, if it is both non-conducting and non-polar.Choose the correct statement(s) from the options given below. [NEET 2024]$ (1) $B and D only$ (2) $A and C only$ (3) $A, C and D only$ (4) $C only$ 127. $A step‐up transformer operates on a 230 V line and supplies a load of 2 ampere. The ratio of the primary and secondary windings is 1 : 25 . The current in the primary is$ (1) $15 A$ (2) $50 A$ (3) $25 A$ (4) $12.5 A$ 128. $For a coil having L = 2 mH, current flow through it is I = t^{2} e^{- t} then, the time at which emfbecomes zero$ (1) $2 sec$ (2) $1 sec$ (3) $4 sec$ (4) $3 sec .$ 129. $An ac voltage is applied to a resistance R and an inductor L in series. If R and the inductive reactance are both equal to 3Ω, the phase difference between the applied voltage and the current in the circuit is$ (1) $π /6$ (2) $π /4$ (3) $π /2$ (4) $zero$ 130. $A jet plane of wing span 20 m is travelling towards west at a speed of 400 m s^{- 1} . If the earth's total magnetic field is 4 \times 10^{- 4} T and the dip angle is 30^{\circ}, at that place, the voltage difference developed across the ends of the wing is$ (1) $3.2 V$ (2) $6.4 V$ (3) $1.6 V$ (4) $0.8 V$ 131. $A conducting circular loop is placed in a uniform magnetic field 0.04 T with its plane perpendicular to the magnetic field. The radius of the loop starts shrinking at 2 mm / s . The induced emf in the loop when the radius is 2 cm is$ (1) $4.8 πμV$ (2) $0.8 πμV$ (3) $1.6 πμV$ (4) $3.4 πμV$ 132. $A conducting loop of radius \frac{10}{π} cm is placed perpendicular to a uniform magnetic field of 0.5T. The magnetic field is decreased to zero in 0.5 s at a steady rate. The induced emf in the circular loop at 0.25 s is:$ (1) $emf = 1 mV$ (2) $emf = 10 mV$ (3) $emf = 100 mV$ (4) $emf = 5 mV$ 133. $A rectangular, a square, a circular and an elliptical loop, all in the (x - y) plane, are moving out of a uniform magnetic field with a constant velocity, V = v i . The magnetic field is directed along the negative z axis direction. The induced emf, during the passage of these loops, out of the field region, will not remain constant for$ (1) $the circular and the elliptical loops$ (2) $only the elliptical loop$ (3) $any of the four loops$ (4) $the rectangular, circular and elliptical loops$ 134. $A magnetic field of flux density 1.0 Wb m^{- 2} acts normal to a 80 turn coil of 0.01 m^{2} area. If this coil is removed from the field in 0.2 second, the emf induced in it is$ (1) $0.8 V$ (2) $4 V$ (3) $5 V$ (4) $8 V$ 135. $A flat circular coil has 100 turns of wire of radius 10 cm . A uniform magnetic field exists in a direction perpendicular to the plane of the coil and it grows at a rate of 0.1 T / sec . the induced emf in the coil is:$ (1) $πV$ (2) $10 πV$ (3) $\frac{π}{10} V$ (4) $2 πV$ 136. $The magnetic energy stored in an inductor of inductance 4 μH carrying a current of 2 A is [NEET 2023]$ (1) $4 mJ$ (2) $8 mJ$ (3) $8 μJ$ (4) $4 μJ$ 137. $In a region of magnetic induction B = 1 0^{- 2} tesla, a circular coil of radius 30 cm and resistance π^{2} ohm is rotated about an axis which is perpendicular to the direction of B and which forms a diameter of the coil. If the coil rotates at 200 rpm the amplitude of the alternating current induced in the coil is$ (1) $4 π^{2} mA$ (2) $30 mA$ (3) $6 mA$ (4) $200 mA$ 138. $The induced emf can be produced in a coil by (A) moving the coil with uniform speed inside uniform magnetic field (B) moving the coil with non uniform speed inside uniform magnetic field (C) rotating the coil inside the uniform magnetic field (D) changing the area of the coil inside the uniform magnetic field Choose the correct answer from the options given below:$ (1) $B and C only$ (2) $A and C only$ (3) $C and D only$ (4) $B and D only$ 139. $Two coils A and B have mutual inductance 2 \times 10^{- 2} henry. If the current in the primary is i = 5 sin (10 πt) then the maximum value of emf induced in coil B is$ (1) $π volt$ (2) $\frac{π}{2} volt$ (3) $\frac{π}{3} volt$ (4) $\frac{π}{4} volt$ 140. $Current in a coil changes from 4 A to zero in 0.1 second and the emf induced is 100 V . The self inductance of the coil is$ (1) $0.25 H$ (2) $0.4 H$ (3) $2.5 H$ (4) $4 H$ 141. $The instantaneous values of alternating current and voltages in a circuit are given as i = \frac{1}{2} sin (100 πt) ampere e = \frac{1}{2} sin (100 πt + \frac{π}{3}) Volt .The average power in watts consumed in the circuit is$ (1) $\frac{1}{4}$ (2) $\frac{3}{4}$ (3) $\frac{1}{2}$ (4) $\frac{1}{8}$ 142. $Alternating current of peak value (\frac{2}{π}) ampere flows through the primary coil of the transformer. The coefficient of mutual inductance between primary and secondary coil is 1 henry. The peak e.m.f. induced in secondary coil is (Frequency of a.c. = 50 Hz)$ (1) $100 V$ (2) $200 V$ (3) $300 V$ (4) $400 V$ 143. $A cycle wheel of radius 0.5 m is rotated with constant angular velocity of 10 rad / s in a region of magnetic field of 0.1 T which is perpendicular to the plane of the wheel. The EMF generated between its centre and the rim is,$ (1) $0.25 V$ (2) $0.125 V$ (3) $0.5 V$ (4) $zero$ 144. $A capacitor of capacity C has reactance X . If capacitance and frequency become double then reactance will be$ (1) $4 X$ (2) $X /2$ (3) $X /4$ (4) $2 X .$ 145. $A coil of inductive reactance 31Ω has a resistance of 8Ω . It is placed in series with a condenser of capacitive reactance 25Ω . The combination is connected to an a.c. source of 110 V The power factor of the circuit is$ (1) $0.33$ (2) $0.56$ (3) $0.64$ (4) $0.80$ 146. $A long solenoid has 500 turns, when a current of 2 A is passed through it, the resulting magnetic flux linked with each turn of the solenoid is 4 \times 10^{- 3} Wb, then self induction of the solenoid is$ (1) $2.0 henry$ (2) $4.0 henry$ (3) $1.0 henry$ (4) $2.5 henry$ 147. $An inductance coil has a reactance of 100Ω . When an AC signal of frequency 1000 Hz is applied to the coil, the applied voltage leads the current by 45^{\circ} . The self-inductance of the coil is$ (1) $6.7 \times 10^{- 7} H$ (2) $5.5 \times 10^{- 5} H$ (3) $1.1 \times 10^{- 1} H$ (4) $1.1 \times 10^{- 2} H$ 148. $The primary and secondary coils of a transformer have 50 and 1500 turns respectively. If the magnetic flux φ linked with the primary coil is given by φ = φ_{0} + 4 t, where φ is in webers, t is time in seconds and φ_{0} is a constant, the output voltage across the secondary coil is$ (1) $120 volts$ (2) $220 volts$ (3) $30 volts$ (4) $90 volts.$ 149. $Two concentric circular coils, C_{1} and C_{2} are placed in the XY plane. C_{1} has 500 turns, and a radius of 1 cm has 200 . C_{2} turns and radius of 20 cm . C_{2} carries a time dependent current I (t) = (5 t^{2} - 2 t + 3) A where t is in s . The emf induced in C_{1} (in Mv), at the instant t = 1 s is \frac{4}{x} . The value of x is$ 150. $A certain elastic conducting material is stretched into a circular loop. It is placed with its plane perpendicular to a uniform magnetic field B = 0.8 T. When released the radius of the loop starts shrinking at a constant rate of 2 c m s^{- 1} . The induced emf in the loop at an instant when the radius of the loop is 10 cm will be ______mV.$