Alternating Current PYQs Set 8 (PDF)

Set 8 of 10 · Questions 211-240 of 290

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Mere Teacher · Previous Year Questions JEE Main Physics · Alternating Current · Set 8 (Q211-240)
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211. $In the following circuit an AC input Vi (t) = (20 mV) sin (10^{5} t) is applied at the left end. The amplitude of the output voltage V_{0} at the right end across the capacitor will be$ (1) $14.14 mV$ (2) $10.55 mV$ (3) $20.2 mV$ (4) $25.55 mV$ 212. $An ideal resistance R, ideal inductance L, ideal capacitance C and AC volt meters V_{1}, V_{2}, V_{3} and V_{4} are connected to an AC source as shown. At resonance,$ (1) $reading in V_{3} = reading in V_{1}$ (2) $reading in V_{1} = reading in V_{2}$ (3) $reading in V_{2} = reading in V_{4}$ (4) $reading in V_{2} = reading in V_{3}$ 213. $In LC circuit the inductance L = 40 mH and capacitance C = 100 μF . If a voltage V (t) = 10 sin (314 t) is applied to the circuit, the current in the circuit is given as:$ (1) $0.52 cos 314 t$ (2) $10 cos 314 t$ (3) $5.2 cos 314 t$ (4) $0.52 sin 314 t$ 214. $A coil of self-inductance L is connected in series with a bulb B and an AC source. Brightness of the bulb decreases when:$ (1) $number of turns in the coil is reduced.$ (2) $a capacitance of reactance X_{C} = X_{L} is included in the same circuit$ (3) $an iron rod is inserted in the coil$ (4) $frequency of the AC source is decreased$ 215. $In the given electrical circuit, if the switch S is closed then the maximum energy stored in the inductors is:$ (1) $3 J$ (2) $9 J$ (3) $12 J$ (4) $6 J$ 216. $Total impedance of a series LCR circuit varies with angular frequency of the AC source connected to it as shown in the graph. The quality factor Q of the series LCR circuit is$ (1) $0.4$ (2) $2.5$ (3) $5$ (4) $1$ 217. $Find the peak current and resonant frequency of the following circuit (as shown in figure)$ (1) $0.2 A and 100 Hz$ (2) $2 A and 50 Hz$ (3) $2 A and 100 Hz$ (4) $0.2 A and 50 Hz$ 218. $For a series LCR circuit, I vs ωrcurve is shown: (A) To the left of ωr, the circuit is mainly capacitive. (B) To the left of ωr, the circuit is mainly inductive. (C) At ωr, impedance of the circuit is equal to the resistance of the circuit. (D) At ωr, impedance of the circuit is 0. Choose the most appropriate answer from the options given below:$ (1) $(A) and (D) only$ (2) $(B) and (D) only$ (3) $(A) and (C) only$ (4) $(B) and (C) only$ 219. $Figure shows a circuit that contains four identical resistors with resistance R = 2.0Ω . TWo identical inductorswith inductance L = 2.0 mH and an ideal battery with emf E = 9. V . The current ’ i ’ just after the switch ’ s ’ isclosed will be:$ (1) $9 A$ (2) $3.0 A$ (3) $2.25 A$ (4) $3.37 A$ 220. $An ac voltage of 10 sin ωt volt is applied to a pure inductor of inductance 10 H . The current through the inductor in ampere is$ (1) $\frac{1}{ω} sin (ωt - \frac{π}{2})$ (2) $ω sin (ωt - \frac{π}{2})$ (3) $\frac{1}{ω ^{2}} sin (ωt - \frac{π}{2})$ (4) $ω^{2} sin (ωt - \frac{π}{2})$ 221. $A resistor and a capacitor are connected in series with an a.c. source. If the potential drop across the capacitor is 5 V and that across resistor is 12 V, the applied voltage is$ (1) $13 V$ (2) $17 V$ (3) $5 V$ (4) $12 V$ 222. $A coil of negligible resistance is connected in series with 90Ω resistor across 120 V, 60 Hz supply. A voltmeter reads 36 V across resistance. Inductance of the coil is:$ (1) $0.286 H$ (2) $0.76 H$ (3) $2.86 H$ (4) $0.91 H$ 223. $An RC circuit as shown in the figure is driven by a AC source generating a square wave. The output wave pattern monitored by CRO would look close to:$ (1) (2) (3) (4) 224. $The readings of ammeter and voltmeter in the following circuit are respectively$ (1) $2.7 A, 220 V$ (2) $1.2 A, 120 V$ (3) $2.2 A, 220 V$ (4) $1.5 A, 100 V$ 225. $In the given circuit, rms value of current (I_{r m s}) through the resistor R is:$ (1) $2A$ (2) $\frac{1}{2} A$ (3) $20 A$ (4) $22 A$ 226. $A series L,R circuit connected with an ac source E = (25 sin 1000 t) V has a power factor of \frac{1}{2} . If the source of emf is changed to E = (20 sin 2000 t) V, the new power factor of the circuit will be:$ (1) $\frac{1}{2}$ (2) $\frac{1}{3}$ (3) $\frac{1}{5}$ (4) $\frac{1}{7}$ 227. $In the given circuit, the resomant frequency is$ (1) $1592 Hz$ (2) $15910 Hz$ (3) $15.92 Hz$ (4) $159.2 Hz$ 228. $At very high frequencies, the current (i) in the given circuit is$ (1) $4 A$ (2) $0.4 A$ (3) $44 A$ (4) $4.4 A$ 229. $For an RLC circuit driven with voltage of amplitude υ_{m} and frequency ω_{0} = \frac{1}{LC} the current exhibits resonance. The quality factor, Q is given by:$ (1) $\frac{R}{( ω _{0} C )}$ (2) $\frac{CR}{ω _{0}}$ (3) $\frac{ω _{0} L}{R}$ (4) $\frac{ω _{0} R}{L}$ 230. $To light, a 50 W, 100 V lamp is connected, in 50 series with a capacitor of capacitance \frac{50}{π x} μF with 200 V, 50Hz AC source. The value of x will be____.$ 231. $An ac source is connected in given series LCR circuit. The rms potential difference across the capacitor of 20 μF is____V.$ 232. $A capacitor of reactance 43 Ω and a resistor of resistance 4Ω are connected in series with an ac source of peak value 82 V . The power dissipation in the circuit is______ W.$ 233. $As shown in the figure an inductor of inductance 200 mH is connected to an AC source of emf 220 V and frequency 50 Hz. The instantaneous voltage of the source is 0 V when the peak value of current is \frac{a}{π} A . The value of a is$ 234. $In the circuit shown in the figure, the ratio of the quality factor and the band width is s.$ 235. $A 110 V, 50 Hz, AC source is connected in the circuit (as shown in figure). The current through the resistance 55 Ω, at resonance in the circuit, will be A.$ 236. $Using a variable frequency a.c. voltage source the maximum current measured in the given LCR circuit is 50 mA for V = 5 sin (100 t) The values of L and R are shown in the figure. The capacitance of the capacitor (C) used is____μF .$ 237. $An AC source is connected to an inductance of 100 mH, a capacitance of 100 μ F and a resistance of 120 Ω as shown in figure. The time in which the resistance having a thermal capacity 2 J°/C will get heated by 16°C is ________ s.$ 238. $In the given figure, the charge stored in 6µF capacitor, when points A and B are joined by a connecting wire is µC.$ 239. $An ac circuit has an inductor and a resistor R of resistance in series, such that X_{L} = 3 R . Now, a capacitor is added in series such that X_{C} = 2 R . The ratio of new power factor with the old power factor of the circuit is 5 : x . The value of x is$ 240. $For ac circuit shown in figure, R = 100 kΩ and C = 100 pF and the phase difference between V_{in} and (V_{B} - V_{A}) is 90^{\circ} . The input signal frequency is 10^{x} rad / sec, where ' x' is _______.$