Electromagnetic Induction PYQs Set 5 (PDF)

Set 5 of 10 · Questions 121-150 of 274

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Mere Teacher · Previous Year Questions NEET Physics · Electromagnetic Induction · Set 5 (Q121-150)
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121. $A flat circular coil has 100 turns of wire of radius 10 cm . A uniform magnetic field exists in a direction perpendicular to the plane of the coil and it grows at a rate of 0.1 T / sec . the induced emf in the coil is:$ (1) $πV$ (2) $10 πV$ (3) $\frac{π}{10} V$ (4) $2 πV$ 122. $The magnetic energy stored in an inductor of inductance 4 μH carrying a current of 2 A is [NEET 2023]$ (1) $4 mJ$ (2) $8 mJ$ (3) $8 μJ$ (4) $4 μJ$ 123. $In a region of magnetic induction B = 1 0^{- 2} tesla, a circular coil of radius 30 cm and resistance π^{2} ohm is rotated about an axis which is perpendicular to the direction of B and which forms a diameter of the coil. If the coil rotates at 200 rpm the amplitude of the alternating current induced in the coil is$ (1) $4 π^{2} mA$ (2) $30 mA$ (3) $6 mA$ (4) $200 mA$ 124. $The induced emf can be produced in a coil by (A) moving the coil with uniform speed inside uniform magnetic field (B) moving the coil with non uniform speed inside uniform magnetic field (C) rotating the coil inside the uniform magnetic field (D) changing the area of the coil inside the uniform magnetic field Choose the correct answer from the options given below:$ (1) $B and C only$ (2) $A and C only$ (3) $C and D only$ (4) $B and D only$ 125. $Two coils A and B have mutual inductance 2 \times 10^{- 2} henry. If the current in the primary is i = 5 sin (10 πt) then the maximum value of emf induced in coil B is$ (1) $π volt$ (2) $\frac{π}{2} volt$ (3) $\frac{π}{3} volt$ (4) $\frac{π}{4} volt$ 126. $Current in a coil changes from 4 A to zero in 0.1 second and the emf induced is 100 V . The self inductance of the coil is$ (1) $0.25 H$ (2) $0.4 H$ (3) $2.5 H$ (4) $4 H$ 127. $The instantaneous values of alternating current and voltages in a circuit are given as i = \frac{1}{2} sin (100 πt) ampere e = \frac{1}{2} sin (100 πt + \frac{π}{3}) Volt .The average power in watts consumed in the circuit is$ (1) $\frac{1}{4}$ (2) $\frac{3}{4}$ (3) $\frac{1}{2}$ (4) $\frac{1}{8}$ 128. $Alternating current of peak value (\frac{2}{π}) ampere flows through the primary coil of the transformer. The coefficient of mutual inductance between primary and secondary coil is 1 henry. The peak e.m.f. induced in secondary coil is (Frequency of a.c. = 50 Hz)$ (1) $100 V$ (2) $200 V$ (3) $300 V$ (4) $400 V$ 129. $A cycle wheel of radius 0.5 m is rotated with constant angular velocity of 10 rad / s in a region of magnetic field of 0.1 T which is perpendicular to the plane of the wheel. The EMF generated between its centre and the rim is,$ (1) $0.25 V$ (2) $0.125 V$ (3) $0.5 V$ (4) $zero$ 130. $A capacitor of capacity C has reactance X . If capacitance and frequency become double then reactance will be$ (1) $4 X$ (2) $X /2$ (3) $X /4$ (4) $2 X .$ 131. $A coil of inductive reactance 31Ω has a resistance of 8Ω . It is placed in series with a condenser of capacitive reactance 25Ω . The combination is connected to an a.c. source of 110 V The power factor of the circuit is$ (1) $0.33$ (2) $0.56$ (3) $0.64$ (4) $0.80$ 132. $A long solenoid has 500 turns, when a current of 2 A is passed through it, the resulting magnetic flux linked with each turn of the solenoid is 4 \times 10^{- 3} Wb, then self induction of the solenoid is$ (1) $2.0 henry$ (2) $4.0 henry$ (3) $1.0 henry$ (4) $2.5 henry$ 133. $An inductance coil has a reactance of 100Ω . When an AC signal of frequency 1000 Hz is applied to the coil, the applied voltage leads the current by 45^{\circ} . The self-inductance of the coil is$ (1) $6.7 \times 10^{- 7} H$ (2) $5.5 \times 10^{- 5} H$ (3) $1.1 \times 10^{- 1} H$ (4) $1.1 \times 10^{- 2} H$ 134. $The primary and secondary coils of a transformer have 50 and 1500 turns respectively. If the magnetic flux φ linked with the primary coil is given by φ = φ_{0} + 4 t, where φ is in webers, t is time in seconds and φ_{0} is a constant, the output voltage across the secondary coil is$ (1) $120 volts$ (2) $220 volts$ (3) $30 volts$ (4) $90 volts.$ 135. $The magnetic flux linked with a coil (in Wb) is given by the equation φ = 5 t^{2} + 3 t + 16 The magnitude of induced emf in the coil at the fourth second will be [NEET 2020]$ (1) $33 V$ (2) $43 V$ (3) $108 V$ (4) $10 V$ 136. $The self induced emf of a coil is 25 volts. When the current in it is changed at uniform rate from 10A to 25A in 1s, the change in the energy of the inductance is:$ (1) $540 J$ (2) $740 J$ (3) $637.5 J$ (4) $437.5 J$ 137. $A straight line conductor of length 0.4 m is moved with a speed of 7 m / s perpendicular to a magnetic field of intensity 0.9 Wb / m^{2} . The induced e.m.f. across the conductor is$ (1) $5.04 V$ (2) $25.2 V$ (3) $1.26 V$ (4) $2.52 V$ 138. $A square loop of side 1 m and resistance 1Ω placed in a magnetic field of 0.5 T. If the plane of loop is perpendicular to the direction of magnetic field, the magnetic flux through the loop is [NEET 2022]$ (1) $0.5 Wb$ (2) $1 Wb$ (3) $zero Wb$ (4) $2 Wb$ 139. $A circular loop of radius 7 cm is placed in uniform magnetic field of 0.2 T directed perpendicular to plane of loop. The loop is converted into a square loop in 0.5 s. The EMF induced in the loop is____mV.$ (1) $13.2$ (2) $1.32$ (3) $8.25$ (4) $6.6$ 140. $An emf of 0. 08 V is induced in a metal rod of length 10 cm held normal to a uniform magnetic field of 0.4 T, when move with a velocity of:$ (1) $0. 5 m s^{- 1}$ (2) $20 m s^{- 1}$ (3) $3. 2 m s^{- 1}$ (4) $2 m s^{- 1}$ 141. $Two coils A and B have mutual inductance 0.008 H . The current changes in the coil A, according to the equation I = I_{m} sin ωt, where I_{m} = 5Λ and ω = 200 πrad s^{- 1} . The maximum value of the e.m.f. induced in the coil B in volt is$ (1) $4 π$ (2) $8 π$ (3) $10 π$ (4) $16 π$ 142. $A 800 turn coil of effective area 0.05 m^{2} is kept perpendicular to a magnetic field 5 \times 1 0^{-5} T. When the plane of the coil is rotated by 90º around any of its coplanar axis in 0.1 s, the emf induced in the coil will be:$ (1) $0.02 V$ (2) $2 V$ (3) $0.2 V$ (4) $2 \times 1 0^{-3} V$ 143. $When a current ' i' through a solenoid is increasing at a constant rate then the induced current is$ (1) $Constant and it will be in the direction of ' i'$ (2) $Constant and it will be in a direction opposite to the 'i'$ (3) $Increases with time and it will be in the direction of 'i'$ (4) $Increases with time and opposite to the direction of 'i'$ 144. $The primary winding of a transformer has 500 turns whereas its secondary has 5000 turns. The primary is connected to an A.C. supply of 20 V, 50 Hz. The secondary will have an output of$ (1) $2 V, 50 Hz$ (2) $2 V, 5 Hz$ (3) $200 V, 50 Hz$ (4) $200 V, 500 Hz$ 145. $A series L - R circuit is connected to a battery of emf V . If the circuit is switched on at t = 0, then the time at which the energy stored in the inductor reaches (\frac{1}{n}) times of its maximum value, is$ (1) $\frac{L}{R} ln (\frac{n + 1}{n - 1})$ (2) $\frac{L}{R} ln (\frac{n}{n - 1})$ (3) $\frac{L}{R} ln (\frac{n}{n + 1})$ (4) $\frac{L}{R} ln (\frac{n - 1}{n})$ 146. $The current in a coil of inductance 0.2 H changes from 5 A to 2 A in 0.5 sec . The magnitude of the average induced emf in the coil is$ (1) $30 V$ (2) $0.3 V$ (3) $0.6 V$ (4) $1.2 V$ 147. $An ideal transformer converts 220 V a.c. to 3.3 kV a.c. to transmit a power of 4.4 kW . If primary coil has 600 turns, then alternating current in secondary coil is$ (1) $\frac{1}{3} A$ (2) $\frac{4}{3} A$ (3) $\frac{5}{3} A$ (4) $\frac{7}{3} A$ 148. $Which of the following combinations should be selected for better tuning of an L - C - R circuit used for communication?$ (1) $R = 20Ω, L = 1.5 H, C = 35 μF$ (2) $R = 25Ω, L = 2.5 H, C = 45 μF$ (3) $R = 15Ω, L = 3.5 H, C = 30 μF$ (4) $R = 25Ω, L = 1.5 H, C = 45 μF$ 149. $A rectangular loop of length 2.5 m and width 2 m is placed at 60^{\circ} to a magnetic field of 4 T . The loop is removed from the field in 10 sec. The average emf induced in the loop during this time is$ (1) $- 2 V$ (2) $+ 2 V$ (3) $+ 1 V$ (4) $- 1 V$ 150. $Two cables of copper are of equal lengths. One of them has a single wire of area of cross‐section A, while other has 10 wires of cross‐sectional area A /10 each. Give their suitability for transporting A.C. and D.C.$ (1) $only multiple strands for A.C., either for D.C.$ (2) $only multiple strands for A.C., only single strand for D.C.$ (3) $only single strand for D.C., either for A.C.$ (4) $only single strand for A.C., either for D.C.$