Title 2. ALTERNATING CURRENT - LEVEL-V_Final (PART-I) (68-84).pdf ✅

ALTERNATING CURRENT 6 8 NISHITH Multimedia India (Pvt.) Ltd., NISHITH Multimedia India (Pvt.) Ltd., JEE ADVANCED - VOL-VII LEVEL-V SINGLE ANSWER QUESTIONS 1. The value of current in two series L C R circuits at resonance is same when connected across a sinusodial voltage source. Then: A. both circuits must be having same value of capacitance and inductor B. in both circuits ratio of L and C will be same C. for both the circuits / X X L C must be same at that frequency D. both circuits must have same impedance at all frequencies 2. The series RLC circuit in resonance is called: A. Selector circuit B. rejector circuit C. amplifier circuit D. oscilla tor circuit 3. In a series R-L-C circuit, the frequency of the source is half of the resonance frequency. The nature of the circuit will be a) capacitive b) inductive c) purely resistive d) selective RMS & Average value of Alternating current 4. The instantaneous value of current and emf in an AC circuit are  1 I sin314t amp 2 and          E 2 sin 314t V 6 , respectively. The phase difference between E and I (with respect to I) will be A) 6   rad B) 3   rad C) 6  rad D) 3  rad 5. The r.m.s. value of an ac of 50 Hz is 10 amp. The time taken by the alternating current in reaching from zero to maximum value and the peak value of current will be A) 2 × 10–2 sec and 14.14 amp B) 1 × 10–2 sec and 7.07 amp C) 5 × 10–3 sec and 7.07 amp D) 5 × 10–3 sec and 14.14 amp 6. The voltage time (V-t) graph for a triangular wave having peak value Vo is as shown in figure. The rms value of V is V Vo Vo T/4 T 2T t A) Vo 3 B) Vo 2 C) Vo 2 D) Vo 3 7. The average value for the saw-tooth voltage of peak value of V0 as shown in figure is a) 0 3 V b) 0 2 V c) 0 2 3 V d) 0 2 V 8. An alternating voltage is given by: 1 2 e e sin t e cos t     Then the root mean square value of voltage is given by: A) 2 2 1 2 e e  B) 1 2 e e C) 1 2 e e 2 D) 2 2 1 2 e e 2  AC across L-R, L-C,L-C-R circuits 9. When 100 volt DC is applied across a solenoid, a current of 1.0 amp flows in it. When 100 volt AC is applied across the same coil, the current drops to 0.5 amp. If the frequency of the AC source is 50 Hz, the impedance and inductance of the solenoid are A) 200 ohm and 0.55 henry B) 100 ohm and 0.86 henry C) 100 ohm and 1.0 henry D) 100 ohm and 0.93 henry. ALTERNATING CURRENT
NISHITH Multimedia India (Pvt.) Ltd., 6 9 JEE - ADVANCED - VOL - CURRENT ELECTRICITY NISHITH Multimedia India (Pvt.) Ltd., JEE ADVANCED - VOL-VII ALTERNATING CURRENT 10. A coil having an inductance of 1/  henry is connected in series with a resistance of 300 . If 20 volt from a 200 cycle source are impressed across the combination, the value of the phase angle between the voltage and the current is : A) 1 5 tan 4  B) 1 4 tan 5  C) 1 3 tan 4  D) 1 4 tan 3  . 11. In a circuit containing an inductance of zero resistance, the current leads the applied a.c. voltage by a phase angle at A) 90o B) -90o C) 0o D) 180o 12. In RLC circuit, at a frequency , the potential difference across each device are  R max V = 8.8 V,  L max   V 2.6 V and  C max   V 7.4 V . The composed potential difference  C L max    V V across inductor and capacitor is A) 10 V B) 7.8 V C) 7.4 V D) 4.8 V 13. The natural frequency of the circuit shown in the figure is A) 1 2 LC  B) 1  LC C) 2  LC D) none 14. If the phase difference between voltage and current is / 6 and the resistance in the circuit is 300  , then the impedance of the circuit will be A) 40 B) 20 C) 50 D) 13 15. In the circuit as shown in the figure, if value of R 60   , then the current flowing through the condenser will be ~ L C 20V 10V R 15V A) 0.5 A B) 0.25 A C) 0.75 A D) 1.0 A 16. The power in ac circuit is given by P = ErmsI rmscosf.The vale of cos f in series LCR circuit at resonance is: A) zero B) 1 C) 2 1 D) 2 1 17. A generator with an adjustable frequency of oscillation is connected to resistance, R = 100, inductances, L1 = 1.7 mH and L2 = 2.3 mH and capacitances, C 4 F 1   , C 2.5 F 2   and C 3.5 F 3   . The resonant angular frequency of the circuit is A) 0.5 rad/s B) 4 0.5 10 rad/ s  C) 2 rad/s D) 4 2 10 rad/ s   18. In the a.c. circuit shown in figure, the supply voltage has a constant r.m.s. values but variable frequency f. Resonance frequency is A) 10 Hz B) 100 Hz C) 1000 Hz D) 200 Hz 19. In a LCR circuit capacitance is changed from C to 2C. For the resonant frequency to remain unchanged, the inductance should be change from L to A) 4L B) 2L C) L/2 D) L/4 20. In an a.c. circuit V and i are given by V = 100sin 100t volts;   i 100sin 100t mA 3          . The power dissipated in the circuit is A) 104 watt B) 10 watt C) 2.5 watt D) 5 watt
ALTERNATING CURRENT 7 0 NISHITH Multimedia India (Pvt.) Ltd., NISHITH Multimedia India (Pvt.) Ltd., JEE ADVANCED - VOL-VII 21. A series combination of R, L, C is connected to an a.c. source. If the reistance is 3 and the reactance is 4 , the power factor of the circuit is A) 0.4 B) 0.6 C) 0.8 D) 1.0 22. If a current I given by I sin( t / 2) 0    flows in an ac circuit across which an ac potential of E sin( t) 0  has been applied, then the power consumption P in the circuit will be A) E0 I0 / 2 B) E I 2 0 0 / C) EI/ 2 D) Zero 23. If i t 0 t T 2  ,   then rms value of current is A) 2 T 2 B) 2 T 2 C) 5 T 2 D) 2 5 T 24. In a series CR circuit shown in figure, the applied voltage is 10 V and the voltage across capacitor is found to be 8V. Then the voltage across R, and the phase difference between current and the applied voltage will respectively be A) 6V, tan–1       3 4 B) 3V, tan–1       4 3 C) 6V, tan–1       3 5 D) 1 4 3 , tan 3 V        25. An inductor of inductance L and resistor of resistance R are joined in series and connected by a source of emf V and frequency . Power dissipated in the circuit is A) V R L 2 2 2 (   ) B) ( ) 2 2 2 2 R L V R   C) ( ) 2 2 2 R L V   D) 2 2 2 2 V R   L 26. Power loss in AC circuit will be minimum when A) Inductance is high, resistance is high B) Inductance is low, resistance is high C) Inductance is low, resistance is low D) Inductance is high, resistance is low 27. In the circuit, as shown in the figure, if the value of R.M.S current is 2.2 ampere, the power factor of the box is A) 2 1 B) 1 C) 2 3 D) 2 1 28. The impedance of a series RL circuit is same as the series RC circuit when connected to the same AC source separately keeping the same resistance. The frequency of the source is A) 1 LC B) 1 2 LC C) R L D) 1 RC 29. A current source sends a current i i t  0 cos . When connected across an unknown load gives a voltage output of, v v t   0 sin / 4    across that load. Then voltage across the current source may be brought in phase with the current through it by: a) Connecting an inductor in series with the load b) Connecting a capacitor in series with the load c) Connecting a capacitor in parallel with the load d) Connecting a capacitor in parallel with the load
NISHITH Multimedia India (Pvt.) Ltd., 7 1 JEE - ADVANCED - VOL - CURRENT ELECTRICITY NISHITH Multimedia India (Pvt.) Ltd., JEE ADVANCED - VOL-VII ALTERNATING CURRENT 30. A combination of elements is enclosed in a black box and the voltage and currents are measured across this black box. The expression for applied voltage; and the current flowing in it is i t   2 2 sin / 4     where   100 rad/sec. Then the wrong statement is: a) There must be a capacitor is the black box b) Power factor of circuit = 0.707 c) There must be a resistor in the box d) There must be an inductor in the box 31. A high impedance AC voltmeter is connected in turn across the inductor, the capacitor and the resistor in a series circuit having an AC source of 100 V(rms) and gives the same reading in volts in each case. This reading is: a) 100 V b) 141 V c) 150 V d) 200 V 32. In a black box of unknown elements (L, C or R or any other combination) an AC voltage   0 E E t   sin   is applied and current in the circuit was found to be i i t    0 sin / 4    . Then the unknown elements in the box may be: A) only capacitor B) inductor and resistor both C) either capacitor, resistor and inductor or only capacitor and resistor D) only resistor 33. A given alternating current has an rms value of 5.6 ampere. If this current flows in a curcuit containing 10 of resistance in series with 20of inductive reactance, the power consumed in the circuit will be A) 313.6 W B) 940.8 W C) 627.2 W D) 168 W 34. In an a.c.circuit, V & I are given by V = 100 sin (100 t) volt. 100sin 100 2 I t mA          The power dissipated in the circuit is: A) 1 watt B) 10 watt C) zero D) 5 watt 35. The rms current value of a semicircular wave which has a maximum value 0 i is X Y -i0 +i0 A. 0 3 i B. 0 2 3 i C. 0 2 i D. 0 2i 36. The rms and the average value of the voltage wave shown in figure are t V 1 2 3 4 0 -2 -4 2 A. 32 V;1 3 V B. 11V;1 3 V C. 11V;3 3 V D. 32 V;3 3 V 37. In R-L-C series circuit, we have same current at angular frequencies 1 and 2 . The resonant frequency of circuit is A. 2 1 2   B. 2 2 1   C.  1 2 D.    1 2 38. A choke coil of resistance R and inductance L is connected to an A.C. source of frequency f and maximum voltage V0 . Then, the average power dissipated in the choke is proportional to: A. 2 f B. 2 f  C. 1 f D. 0 f