Alternating Current PYQs Set 6 (PDF)

Set 6 of 9 · Questions 151-180 of 244

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Mere Teacher · Previous Year Questions NEET Physics · Alternating Current · Set 6 (Q151-180)
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151. $In a series LCR circuit, the potential drop across L, C and R respectively are 40 V, 120 V and 60 V . Then the source voltage is$ (1) $220 V$ (2) $160 V$ (3) $180 V$ (4) $100 V$ 152. $In an AC circuit, the current is i = 5 sin (100 t - \frac{π}{2}) A and voltage is e = 200 sin (100 t) volt. Power consumption in the circuit is (cos 90^{\circ} = 0)$ (1) $200 W$ (2) $0 W$ (3) $40 W$ (4) $1000 W$ 153. $For a purely inductive or a purely capacitive circuit, the power factor is$ (1) $zero$ (2) $0.5$ (3) $1$ (4) $\infty$ 154. $In a series LCR circuit, an alternating emf (v) and current (i) are given by the equation v = v_{0} sin ωt, i = i_{0} sin (ωt + \frac{π}{3}) . The average power dissipated in the circuit over a cycle of AC is$ (1) $\frac{v _{0} i _{0}}{2}$ (2) $\frac{v _{0} i _{0}}{4}$ (3) $\frac{3}{2} v_{0} i_{0}$ (4) $Zero$ 155. $Match List-I with List-II List-I (A) AC generator (B) Galvanometer (C) Transformer (D) Metal detector List-II (I) Detects the presence of current in the circuit (II) Converts mechanical energy into electrical energy (III) Works on the principle of resonance in AC circuit (IV) Changes an alternating voltage for smaller or greater value Choose the correct answer from the options given below:-$ (1) $(A)-(II), (B)-(I), (C)-(IV), (D)-(III)$ (2) $(A)-(II), (B)-(I), (C)-(III), (D)-(IV)$ (3) $(A)-(III), (B)-(IV), (C)-(III), (D)-(I)$ (4) $(A)-(III), (B)-(I), (C)-(II), (D)-(IV)$ 156. $In series LCR circuit R = 18Ω and impedance is 33Ω . An rms voltage 220 V is applied across the circuit. The true power consumed in a.c. circuit is$ (1) $220 W$ (2) $400 W$ (3) $600 W$ (4) $800 W$ 157. $An inductor and a resistor of 25Ω are connected in series to an ac source of voltage 100 sin (100 πt) volt. If the impedance of the circuit is 50Ω, the average power dissipated per cycle in the circuit is$ (1) $10 W$ (2) $25 W$ (3) $50 W$ (4) $100 W$ 158. $An alternating voltage of frequency ' ω' is induced in electric circuit consisting of an inductance ' L' and capacitance ' C', connected in parallal. Then across the inductance coil$ (1) $current is maximum when ω^{2} = \frac{1}{LC}$ (2) $current is zero$ (3) $voltage is minimum when ω^{2} = \frac{1}{LC}$ (4) $voltage is maximum when ω^{2} = \frac{1}{LC}$ 159. $To increase the resonant frequency in series LCR circuit,$ (1) $Source frequency should be increased$ (2) $Another resistance should be added in series with the first resistance.$ (3) $Another capacitor should be added in series with the first capacitor$ (4) $The source frequency should be decreased$ 160. $In an a.c. circuit, voltage and current are given by : V = 100 sin (100 t) V and I = 100 sin (100 t + \frac{π}{3}) mA respectively. The average power dissipated in one cycle is :$ (1) $5 W$ (2) $10 W$ (3) $2.5 W$ (4) $25 W$ 161. $A resonant frequency of a current is f . If the capacitance is made four times the initial value, then the resonant frequency will become$ (1) $\frac{f}{2}$ (2) $2 f$ (3) $f$ (4) $\frac{f}{4}$ 162. $The instantaneous value of current and voltage in an AC circuit are given by I = 6 sin (100 πt + π /4) and V = 5 sin (100 πt - π /4) then$ (1) $voltage leads the current by 45^{\circ}$ (2) $current leads the voltage by 45^{\circ}$ (3) $voltage leads the current by 90^{\circ}$ (4) $current leads the voltage by 90^{\circ}$ 163. $The reactance of capacitor at 50 Hz is 5Ω . If the frequency is increased to 100 Hz, the new reactance is$ (1) $5Ω$ (2) $10Ω$ (3) $2.5Ω$ (4) $125Ω$ 164. $When an inductor L and a resistor R in series are connected across a 12 V, 50 Hz supply, a current of 0.5 A flows in the circuit. The current differs in the phase from applied voltage by \frac{π}{3} radian. Then the value of R is$ (1) $10Ω$ (2) $3Ω$ (3) $12Ω$ (4) $15Ω$ 165. $A series LCR circuit contains inductance 5 mH, capacitance 2 μF and resistance 10Ω . If a frequency A.C. source is varied, what is the frequency at which maximum power is dissipated?$ (1) $\frac{2}{π} \times 10^{5} Hz$ (2) $\frac{10 ^{5}}{π} Hz$ (3) $\frac{5}{π} \times 10^{3} Hz$ (4) $\frac{10 ^{- 5}}{π} Hz$ 166. $A resistor of 500Ω, an inductance of 0.5 H are in series with an a.c. which is given by V = 1002 sin (1000 t) . The power factor of the combination is$ (1) $\frac{1}{2}$ (2) $\frac{1}{3}$ (3) $0.5$ (4) $0.6$ 167. $A circuit of negligible resistance has an inductor of 0.16 H and capacitor of 25 μF connected in series with an alternating voltage source. The resonating frequency of the circuit is$ (1) $\frac{200}{π}$ (2) $\frac{250}{π}$ (3) $\frac{400}{π}$ (4) $\frac{150}{π}$ 168. $A resistor of 100Ω, an inductor of \frac{25}{π ^{2}} mH and a capacitor of 0.1 μF are connected in series to an ac source. The impedance of the circuit is minimum for a frequency of$ (1) $5 kHz$ (2) $10 kHz$ (3) $15 kHz$ (4) $20 kHz$ 169. $A step-up transformer operates on a 230 V line and a load current of 2 A . The ratio of primary and secondary windings is 1 : 25 . Then the current in the primary is$ (1) $25 A$ (2) $50 A$ (3) $15 A$ (4) $12.5 A$ 170. $The power factor of R - L circuit is \frac{1}{3} . If the inductive reactance is 2Ω . The value of resistance is$ (1) $0.5Ω$ (2) $\frac{1}{2} Ω$ (3) $2Ω$ (4) $2 Ω$ 171. $In an A.C. circuit, V and I are given by V = 150 sin (150 t) volt and I = 150 sin (150 t + \frac{π}{3}) ampere. The power dissipated in the circuit is$ (1) $106 W$ (2) $150 W$ (3) $5625 W$ (4) $zero$ 172. $A 12 V, 60 W lamp is connected to the secondary of a step down transformer, whose primary is connected to AC mains of 220 V. Assuming the transformer to be ideal, what is the current in the primary winding? [NEET 2023]$ (1) $2.7 A$ (2) $3.7 A$ (3) $0.37 A$ (4) $0.27 A$ 173. $A coil of inductive reactance 1/ 3 Ω and resistance 1Ω is connected to a 200 V, 50 Hz A.C. supply: The time lag between maximum voltage and current is$ (1) $\frac{1}{600} s$ (2) $\frac{1}{200} s$ (3) $\frac{1}{300} s$ (4) $\frac{1}{500} s$ 174. $A resistance R draws power P when connected to an AC source. If an inductance is now placed in series with the resistance, such that the impedance of the circuit becomes Z the power drawn will be$ (1) $P (\frac{R}{Z})^{2}$ (2) $P \frac{R}{Z}$ (3) $P (\frac{R}{Z})$ (4) $P$ 175. $In CR-circuit the growth of charge on the capacitor is$ (1) $more rapid if the CR is smaller$ (2) $more rapid if the CR is larger$ (3) $independent of CR$ (4) $independent of time$ 176. $An inductor 20 mH, a capacitor 100 μF and a resistor 50Ω are connected in series across a source of emf, V = 10 sin 314 t . The power loss in the circuit is [NEET 2018]$ (1) $0.79 W$ (2) $0.43 W$ (3) $2.74 W$ (4) $1.13 W$ 177. $In an ideal transformer, the turns ratio is \frac{N _{p}}{N _{s}} = \frac{1}{2} . The ratio V_{s} : V_{p} is equal to (the symbols carry their usual meaning) [NEET 2024]$ (1) $1 : 2$ (2) $2 : 1$ (3) $1 : 1$ (4) $1 : 4$ 178. $A capacitor and an inductance coil are connected in separate AC circuits with a bulb glowing in both the circuits. The bulb glows more brightly when$ (1) $an iron rod is introduced into the inductance coil.$ (2) $the number of turns in the inductance coil is increased$ (3) $separation between the plates of the capacitor is increased.$ (4) $a dielectric is introduced into the gap between the plates of the capacitor$ 179. $A resistor of resistance of 100Ω is connected to an AC source ϵ = 10 sin (250 π s^{- 1}) t. The energy dissipated as heat during t = 0 to t = 1 ms is approximately.$ (1) $\frac{0.57}{π} mJ$ (2) $\frac{1.141}{π} mJ$ (3) $1 mJ$ (4) $0.5 mJ$ 180. $A series resonant ac circuit contains a capacitor of 10^{- 6} F and an inductor of 10^{- 4} H . The frequency of electrical oscillations will be$ (1) $\frac{10 ^{5}}{2 π} Hz$ (2) $10^{5} Hz$ (3) $\frac{10}{2 π} Hz$ (4) $10 Hz$