JEE Main & Advanced Physics Alternating Current / प्रत्यावर्ती धारा Question Bank

done ac Circuits Total Questions - 98

• question_answer1)
  Choke coil works on the principle of          [MP PET/PMT 1988]
  A)
             Transient current                done clear
  B)
              Self-induction done clear
  C)
             Mutual induction                done clear
  D)
              Wattless current done clear
  View Solution play_arrow

• question_answer2)
  A choke coil has                                           [RPET 1999; AIIMS 1999]
  A)
             High inductance and low resistance done clear
  B)
             Low inductance and high resistance done clear
  C)
             High inductance and high resistance done clear
  D)
             Low inductance and low resistance done clear
  View Solution play_arrow

• question_answer3)
  Choke coil is used to control                                     [CPMT 1984]
  A)
             ac   done clear
  B)
             dc done clear
  C)
             Both ac and dc                      done clear
  D)
             Neither ac nor dc done clear
  View Solution play_arrow

• question_answer4)
  Current in the circuit is wattless, if
  A)
             Inductance in the circuit is zero done clear
  B)
             Resistance in the circuit is zero done clear
  C)
             Current is alternating done clear
  D)
             Resistance and inductance both are zero done clear
  View Solution play_arrow

• question_answer5)
  The phase angle between e.m.f. and current in LCR series ac circuit is                                     [MP PMT/PET 1998]
  A)
             0 to p / 2                                 done clear
  B)
             p / 4 done clear
  C)
             p / 2                                          done clear
  D)
             p done clear
  View Solution play_arrow

• question_answer6)
  A choke coil is preferred to a rheostat in ac circuit as 
  A)
             It consumes almost zero power done clear
  B)
             It increases current done clear
  C)
             It increases power done clear
  D)
             It increases voltage done clear
  View Solution play_arrow

• question_answer7)
  An alternating e.m.f. is applied to purely capacitive circuit. The phase relation between e.m.f. and current flowing in the circuit is            or In a circuit containing capacitance only [MP PET 1996; AIIMS 1997]
  A)
             e.m.f. is ahead of current by p / 2 done clear
  B)
             Current is ahead of e.m.f. by p / 2 done clear
  C)
             Current lags behind e.m.f. by p done clear
  D)
             Current is ahead of e.m.f. by p done clear
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• question_answer8)
  An ac source is connected to a resistive circuits. Which of the following is true                                    [CPMT 1985]
  A)
             Current leads the voltage and both are in same phase done clear
  B)
             Current lags behind the voltage and both are in same phase done clear
  C)
             Current and voltage are in same phase done clear
  D)
             Any of the above may be true depending upon the value of resistance done clear
  View Solution play_arrow

• question_answer9)
  The average power dissipated in a pure inductor of inductance L when an ac current is passing through it, is [CPMT 1974; RPMT 1997; MP PET 1999]
  A)
             \[\frac{1}{2}L{{I}^{2}}\]    done clear
  B)
             \[\frac{1}{4}L{{I}^{2}}\] done clear
  C)
             \[2\,L{{i}^{2}}\]                    done clear
  D)
             Zero (Inductance of the coil L and current I) done clear
  View Solution play_arrow

• question_answer10)
  An alternating current of frequency \['f\,'\] is flowing in a circuit containing a resistance R and a choke L in series. The impedance of this circuit is [CPMT 1978; MP PMT 1993; MP PET 1999; AIIMS 2000; Pb. PET 2004; RPET 2001, 03]
  A)
             R + 2pfL                                   done clear
  B)
             \[\sqrt{{{R}^{2}}+4{{\pi }^{2}}{{f}^{2}}{{L}^{2}}}\] done clear
  C)
             \[\sqrt{{{R}^{2}}+{{L}^{2}}}\] done clear
  D)
             \[\sqrt{{{R}^{2}}+2\pi fL}\] done clear
  View Solution play_arrow

• question_answer11)
  A resonant ac circuit contains a capacitor of capacitance \[{{10}^{-6}}F\] and an inductor of \[{{10}^{-4}}H.\] The frequency of electrical oscillations will be
  A)
             \[{{10}^{5}}\,Hz\]                done clear
  B)
             10 Hz done clear
  C)
             \[\frac{{{10}^{5}}}{2\pi }Hz\] done clear
  D)
             \[\frac{10}{2\pi }Hz\] done clear
  View Solution play_arrow

• question_answer12)
  Power delivered by the source of the circuit becomes maximum, when                                [DCE 2004]
  A)
             \[\omega L=\omega C\]  done clear
  B)
             \[\omega L=\frac{1}{\omega C}\] done clear
  C)
             \[\omega L=-\,{{\left( \frac{1}{\omega C} \right)}^{2}}\]    done clear
  D)
             \[\omega L=\sqrt{\omega C}\] done clear
  View Solution play_arrow

• question_answer13)
  An alternating voltage is connected in series with a resistance R and an inductance L If the potential drop across the resistance is 200 V and across the inductance is 150 V, then the applied voltage is                                              [CPMT 1990]
  A)
             350 V                                        done clear
  B)
             250 V done clear
  C)
             500 V                                        done clear
  D)
             300 V done clear
  View Solution play_arrow

• question_answer14)
  An inductive circuit contains resistance of 10 W and an inductance of 20 H. If an ac voltage of 120 V and frequency 60 Hz is applied to this circuit, the current would be nearly
  A)
             0.32 amp                                done clear
  B)
             0.016 amp done clear
  C)
             0.48 amp                                done clear
  D)
             0.80 amp done clear
  View Solution play_arrow

• question_answer15)
  Same current is flowing in two alternating circuits. The first circuit contains only inductance and the other contains only a capacitor. If the frequency of the e.m.f. of ac is increased, the effect on the value of the current will be [MP PET 1993]
  A)
             Increases in the first circuit and decreases in the other done clear
  B)
             Increases in both the circuits done clear
  C)
             Decreases in both the circuits done clear
  D)
             Decreases in the first circuit and increases in the other done clear
  View Solution play_arrow

• question_answer16)
  A capacitor is a perfect insulator for
  A)
             Alternating currents          done clear
  B)
             Direct currents done clear
  C)
             Both ac and dc                      done clear
  D)
             None of these done clear
  View Solution play_arrow

• question_answer17)
  In a circuit containing an inductance of zero resistance, the e.m.f. of the applied ac voltage leads the current by [CPMT 1990]
  A)
             90o done clear
  B)
             45o done clear
  C)
             30o done clear
  D)
             0o done clear
  View Solution play_arrow

• question_answer18)
  In a pure inductive circuit or In an ac circuit containing inductance only, the current   [MP PMT 1993; CPMT 1996; Kerala PET 2002]
  A)
             Leads the e.m.f. by 90o done clear
  B)
             Lags behind the e.m.f. by 90o done clear
  C)
             Sometimes leads and sometime lags behind the e.m.f. done clear
  D)
             Is in phase with the e.m.f. done clear
  View Solution play_arrow

• question_answer19)
  A 20 volts ac is applied to a circuit consisting of a resistance and a coil with negligible resistance. If the voltage across the resistance is 12 V, the voltage across the coil is [MP PMT 1989; RPMT 1997]
  A)
             16 volts                                    done clear
  B)
             10 volts done clear
  C)
             8 volts                                      done clear
  D)
             6 volts done clear
  View Solution play_arrow

• question_answer20)
  A resistance of 300 W and an inductance of \[\frac{1}{\pi }\] henry are connected in series to a ac voltage of 20 volts and 200 Hz frequency. The phase angle between the voltage and current is                                                         [Roorkee 1980]
  A)
             \[{{\tan }^{-1}}\frac{4}{3}\]    done clear
  B)
             \[{{\tan }^{-1}}\frac{3}{4}\] done clear
  C)
             \[{{\tan }^{-1}}\frac{3}{2}\]    done clear
  D)
             \[{{\tan }^{-1}}\frac{2}{5}\] done clear
  View Solution play_arrow

• question_answer21)
  The power factor of LCR circuit at resonance is [MP PMT 1991; RPMT 1999; RPET 2001; UPSEAT 1999]
  A)
             0.707                                        done clear
  B)
             1 done clear
  C)
             Zero                                          done clear
  D)
              0.5 done clear
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• question_answer22)
  An inductance of 1 mH a condenser of 10 mF and a resistance of 50 W are connected in series. The reactances of inductor and condensers are same. The reactance of either of them will be
  A)
             100 W                                       done clear
  B)
             30 W done clear
  C)
             3.2 W                                        done clear
  D)
             10 W done clear
  View Solution play_arrow

• question_answer23)
  The natural frequency of a L-C circuit is equal to [CPMT 1978, 97]
  A)
             \[\frac{1}{2\pi }\sqrt{LC}\]      done clear
  B)
             \[\frac{1}{2\pi \sqrt{LC}}\] done clear
  C)
             \[\frac{1}{2\pi }\sqrt{\frac{L}{C}}\]                                 done clear
  D)
             \[\frac{1}{2\pi }\sqrt{\frac{C}{L}}\] done clear
  View Solution play_arrow

• question_answer24)
  An alternating voltage \[E=200\sqrt{2}\sin (100\,t)\] is connected to a 1 microfarad capacitor through an ac ammeter. The reading of the ammeter shall be [NCERT 1984; MNR 1995; MP PET 1999; RPET 1999; UPSEAT 2000]
  A)
             10 mA                                      done clear
  B)
             20 mA done clear
  C)
             40 mA                                      done clear
  D)
             80 mA done clear
  View Solution play_arrow

• question_answer25)
  An ac circuit consists of an inductor of inductance 0.5 H and a capacitor of capacitance 8 mF in series. The current in the circuit is maximum when the angular frequency of ac source is                                                   [CPMT 1986]
  A)
             500 rad/sec                            done clear
  B)
             2 ´ 105 rad/sec done clear
  C)
             4000 rad/sec                         done clear
  D)
             5000 rad/sec done clear
  View Solution play_arrow

• question_answer26)
  The average power dissipation in a pure capacitance in ac circuit is            [DPMT 1987; MP PMT/PET 1998]
  A)
             \[\frac{1}{2}C{{V}^{2}}\]  done clear
  B)
             \[C{{V}^{2}}\] done clear
  C)
             \[\frac{1}{4}C{{V}^{2}}\]  done clear
  D)
             Zero done clear
  View Solution play_arrow

• question_answer27)
  In a region of uniform magnetic induction \[B={{10}^{-2}}\,tesla\], a circular coil of radius 30 cm and resistance p2 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                                               [CBSE PMT 1990]
  A)
             4p2 mA                                    done clear
  B)
             30 mA done clear
  C)
             6 mA                                         done clear
  D)
             200 mA done clear
  View Solution play_arrow

• question_answer28)
  An inductive circuit contains a resistance of 10 ohm and an inductance of 2.0 henry. If an ac voltage of 120 volt and frequency of 60 Hz is applied to this circuit, the current in the circuit would be nearly       [CPMT 1990; MP PET 2002]
  A)
             0.32 amp                                done clear
  B)
             0.16 amp done clear
  C)
             048 amp                                  done clear
  D)
             0.80 amp done clear
  View Solution play_arrow

• question_answer29)
  In a LCR circuit having L = 8.0 henry, C = 0.5 mF and R = 100 ohm in series. The resonance frequency in per second is                                                                      [CPMT 1990]
  A)
             600 radian                              done clear
  B)
             600 Hz done clear
  C)
             500 radian                              done clear
  D)
             500 Hz done clear
  View Solution play_arrow

• question_answer30)
  In LCR circuit, the capacitance is changed from C to 4C. For the same resonant frequency, the inductance should be changed from L to                                   [MP PMT 1986; BHU 1998]
  A)
             2L   done clear
  B)
             L / 2 done clear
  C)
             L / 4                                           done clear
  D)
             4 L done clear
  View Solution play_arrow

• question_answer31)
  A 120 volt ac source is connected across a pure inductor of inductance 0.70 henry. If the frequency of the source is 60 Hz, the current passing through the inductor is [MP PET 1994]
  A)
             4.55 amps                              done clear
  B)
             0.355 amps done clear
  C)
             0.455 amps                            done clear
  D)
             3.55 amps done clear
  View Solution play_arrow

• question_answer32)
  The impedance of a circuit consists of 3 ohm resistance and 4 ohm reactance. The power factor of the circuit is [MP PMT 1994]
  A)
             0.4 done clear
  B)
             0.6 done clear
  C)
             0.8  done clear
  D)
             1.0 done clear
  View Solution play_arrow

• question_answer33)
  L, C and R denote inductance, capacitance and resistance respectively. Pick out the combination which does not have the dimensions of frequency                              [MP PMT 1994]
  A)
             \[\frac{1}{RC}\]                    done clear
  B)
             \[\frac{R}{L}\] done clear
  C)
             \[\frac{1}{\sqrt{LC}}\]       done clear
  D)
             \[\frac{C}{L}\] done clear
  View Solution play_arrow

• question_answer34)
  The power factor of a good choke coil is         [MP PMT 1994]
  A)
             Nearly zero                            done clear
  B)
             Exactly zero done clear
  C)
             Nearly one                             done clear
  D)
             Exactly one done clear
  View Solution play_arrow

• question_answer35)
  If resistance of 100 W , inductance of 0.5 henry and capacitance of \[10\times {{10}^{-6}}F\] are connected in series through 50 Hz ac supply, then impedance is        [BHU 1995]
  A)
             1.876                                        done clear
  B)
             18.76 done clear
  C)
             189.72                                      done clear
  D)
             101.3 done clear
  View Solution play_arrow

• question_answer36)
  An alternating current source of frequency 100 Hz is joined to a combination of a resistance, a capacitance and a coil in series. The potential difference across the coil, the resistance and the capacitor is 46, 8 and 40 volt respectively. The electromotive force of alternating current source in volt is [MP PET 1995]
  A)
             94   done clear
  B)
             14 done clear
  C)
             10   done clear
  D)
             76 done clear
  View Solution play_arrow

• question_answer37)
  A 10 ohm resistance, 5 mH coil and 10 mF capacitor are joined in series. When a suitable frequency alternating current source is joined to this combination, the circuit resonates. If the resistance is halved, the resonance frequency [MP PET 1995]
  A)
             Is halved                                 done clear
  B)
             Is doubled done clear
  C)
             Remains unchanged          done clear
  D)
             In quadrupled done clear
  View Solution play_arrow

• question_answer38)
  L, C and R represent physical quantities inductance, capacitance and resistance respectively. The combination representing dimension of frequency is  [MP PET 1995; DCE 2001]
  A)
             LC   done clear
  B)
             \[{{(LC)}^{-1/2}}\] done clear
  C)
             \[{{\left( \frac{L}{C} \right)}^{-1/2}}\]                            done clear
  D)
             \[\frac{C}{L}\] done clear
  View Solution play_arrow

• question_answer39)
  In a series circuit R = 300 W, L = 0.9 H, C = 2.0 mF and w = 1000 rad/sec. The impedance of the circuit is [MP PMT 1995]
  A)
             1300 W                                     done clear
  B)
             900 W done clear
  C)
             500 W                                       done clear
  D)
             400 W done clear
  View Solution play_arrow

• question_answer40)
  In a L-R circuit, the value of L is \[\left( \frac{0.4}{\pi } \right)\ henry\] and the value of R is 30 ohm. If in the circuit, an alternating e.m.f. of 200 volt at 50 cycles per sec is connected, the impedance of the circuit and current will be                      [MP PET 1996; DPMT 2003]
  A)
             \[11.4\,\Omega ,\,17.5\,A\]   done clear
  B)
             \[30.7\,\Omega ,\,6.5A\] done clear
  C)
             \[40.4\,\Omega ,\,5\,A\] done clear
  D)
             \[50\,\Omega ,\,4A\] done clear
  View Solution play_arrow

• question_answer41)
  The reactance of a coil when used in the domestic ac power supply (220 volt, 50 cycles) is 100 ohm. The self inductance of the coil is nearly                                                   [MP PMT 1996]
  A)
             3.2 henry                                done clear
  B)
             0.32 henry done clear
  C)
             2.2 henry                                done clear
  D)
             0.22 henry done clear
  View Solution play_arrow

• question_answer42)
  In a series LCR circuit, operated with an ac of angular frequency \[\omega \], the total impedance is        [MP PET 1996]
  A)
             \[{{[{{R}^{2}}+{{(L\omega -C\omega )}^{2}}]}^{1/2}}\]        done clear
  B)
             \[{{\left[ {{R}^{2}}+{{\left( L\omega -\frac{1}{C\omega } \right)}^{2}} \right]}^{1/2}}\] done clear
  C)
             \[{{\left[ {{R}^{2}}+{{\left( L\omega -\frac{1}{C\omega } \right)}^{2}} \right]}^{-1/2}}\] done clear
  D)
             \[{{\left[ {{(R\omega )}^{2}}+{{\left( L\omega -\frac{1}{C\omega } \right)}^{2}} \right]}^{1/2}}\] done clear
  View Solution play_arrow

• question_answer43)
  The reactance of a \[25\,\mu F\] capacitor at the ac frequency of 4000 Hz is
  A)
             \[\frac{5}{\pi }\]ohm         done clear
  B)
             \[\sqrt{\frac{5}{\pi }}\]ohm done clear
  C)
             10 ohm                                    done clear
  D)
             \[\sqrt{10}\]ohm done clear
  View Solution play_arrow

• question_answer44)
   The frequency for which a \[5\,\mu F\] capacitor has a reactance of \[\frac{1}{1000}\] ohm is given by                                     [MP PET 1997]
  A)
             \[\frac{100}{\pi }MHz\]    done clear
  B)
             \[\frac{1000}{\pi }Hz\] done clear
  C)
             \[\frac{1}{1000}Hz\]           done clear
  D)
             1000 Hz done clear
  View Solution play_arrow

• question_answer45)
  An e.m.f.\[E=4\cos (1000t)\] volt  is applied to an LR-circuit of inductance 3 mH and resistance 4 ohms. The amplitude of current in the circuit is                                       [MP PMT 1997]
  A)
             \[\frac{4}{\sqrt{7}}A\]      done clear
  B)
             1.0 A done clear
  C)
             \[\frac{4}{7}A\]                    done clear
  D)
             0.8 A done clear
  View Solution play_arrow

• question_answer46)
  In an ac circuit, a resistance of R ohm is connected in series with an inductance L. If phase angle between voltage and current be 45°, the value of inductive reactance will be  [MP PMT/PET 1998]
  A)
             \[\frac{R}{4}\]                      done clear
  B)
             \[\frac{R}{2}\] done clear
  C)
             R done clear
  D)
             Cannot be found with the given data done clear
  View Solution play_arrow

• question_answer47)
  A coil of inductance L has an inductive reactance of \[{{X}_{L}}\] in an AC circuit in which the effective current is I. The coil is made from a super-conducting material and has no resistance. The rate at which power is dissipated in the coil is                [MP PMT 1999]
  A)
             0     done clear
  B)
             \[I{{X}_{L}}\] done clear
  C)
             \[{{I}^{2}}{{X}_{L}}\]          done clear
  D)
             \[IX_{L}^{2}\] done clear
  View Solution play_arrow

• question_answer48)
  The phase difference between the current and voltage of LCR circuit in series combination at resonance is [CPMT 1999; Pb. PET 2001]
  A)
             0     done clear
  B)
             \[\pi /2\] done clear
  C)
             \[\pi \]                                     done clear
  D)
             \[-\pi \] done clear
  View Solution play_arrow

• question_answer49)
  In a series resonant circuit, the ac voltage across resistance R, inductance L and capacitance C are 5 V, 10 V and 10 V respectively. The ac voltage applied to the circuit will be [KCET 1994]
  A)
             20 V                                          done clear
  B)
             10 V done clear
  C)
             5 V done clear
  D)
             25 V done clear
  View Solution play_arrow

• question_answer50)
  When 100 volt dc is applied across a coil, a current of 1 amp flows through it. When 100 volt ac at 50 cycle\[{{s}^{-1}}\] is applied to the same coil, only 0.5 ampere current flows. The impedance of the coil is                                  [Bihar MEE 1995]
  A)
             \[100\,\Omega \]                done clear
  B)
             \[200\,\Omega \] done clear
  C)
             \[300\,\Omega \]                done clear
  D)
             \[400\,\Omega \] done clear
  View Solution play_arrow

• question_answer51)
  The coefficient of induction of a choke coil is 0.1H and resistance is \[12\,\Omega \]. If it is connected to an alternating current source of frequency 60 Hz, then power factor will be [RPET 1997]
  A)
             0.32                                           done clear
  B)
             0.30 done clear
  C)
             0.28                                           done clear
  D)
             0.24 done clear
  View Solution play_arrow

• question_answer52)
  For series LCR  circuit, wrong statement is          [RPMT 1997]
  A)
             Applied e.m.f. and potential difference across resistance are in same phase done clear
  B)
             Applied e.m.f. and potential difference at inductor coil have phase difference of \[\pi /2\] done clear
  C)
             Potential difference at capacitor and inductor have phase difference of \[\pi /2\] done clear
  D)
             Potential difference across resistance and capacitor have phase difference of \[\pi /2\] done clear
  View Solution play_arrow

• question_answer53)
  In a purely resistive ac circuit, the current      [Roorkee 1992]
  A)
             Lags behind the e.m.f. in phase done clear
  B)
             Is in phase with the e.m.f. done clear
  C)
             Leads the e.m.f. in phase done clear
  D)
             Leads the e.m.f. in half the cycle and lags behind it in the other half done clear
  View Solution play_arrow

• question_answer54)
  If an \[8\,\Omega \] resistance and \[6\,\Omega \] reactance are present in an ac series circuit then the impedance of the circuit will be [MP PMT 2003]
  A)
             20 ohm                                    done clear
  B)
             5 ohm done clear
  C)
             10 ohm                                    done clear
  D)
             \[14\sqrt{2}\] ohm done clear
  View Solution play_arrow

• question_answer55)
  A 12 ohm resistor and a 0.21 henry inductor are connected in series to an ac source operating at 20 volts, 50 cycle/second. The phase angle between the current and the source voltage is                                   [BHU 1994]
  A)
             30° done clear
  B)
             40° done clear
  C)
             80° done clear
  D)
             90° done clear
  View Solution play_arrow

• question_answer56)
  What will be the phase difference between virtual voltage and virtual current, when the current in the circuit is wattles [RPET 1996]
  A)
             90° done clear
  B)
             45° done clear
  C)
             180°                                          done clear
  D)
             60° done clear
  View Solution play_arrow

• question_answer57)
  The resonant frequency of a circuit is f. If the capacitance is made 4 times the initial values, then the resonant frequency will become                                                                       [RPET 1996]
  A)
             f / 2                                           done clear
  B)
             2f done clear
  C)
             f      done clear
  D)
             f / 4 done clear
  View Solution play_arrow

• question_answer58)
  In the non-resonant circuit, what will be the nature of the circuit for frequencies higher than the resonant frequency [RPET 1996]
  A)
             Resistive                                 done clear
  B)
             Capacitive done clear
  C)
             Inductive                                done clear
  D)
             None of the above done clear
  View Solution play_arrow

• question_answer59)
  In an ac circuit, the potential difference across an inductance and resistance joined in series are respectively 16 V and 20 V. The total potential difference across the circuit is [AFMC 1998; BHU 1999]
  A)
             20.0 V                                       done clear
  B)
             25.6 V done clear
  C)
             31.9 V                                       done clear
  D)
             53.5 V done clear
  View Solution play_arrow

• question_answer60)
  A 220 V, 50 Hz ac source is connected to an inductance of 0.2 H and a resistance of 20 ohm in series. What is the current in the circuit                                          [MNR 1998; JIPMER 2001, 02]
  A)
             10 A                                          done clear
  B)
             5 A done clear
  C)
             33.3 A                                       done clear
  D)
             3.33 A done clear
  View Solution play_arrow

• question_answer61)
   An LCR circuit contains R = 50 W , L = 1 mH and C = 0.1 mF. The impedance of the circuit will be minimum for a frequency of [Bihar MEE 1995]
  A)
             \[\frac{{{10}^{5}}}{2\pi }{{s}^{-1}}\]                                done clear
  B)
             \[\frac{{{10}^{6}}}{2\pi }{{s}^{-1}}\] done clear
  C)
             \[2\pi \times {{10}^{5}}{{s}^{-1}}\]                                  done clear
  D)
             \[2\pi \times {{10}^{6}}{{s}^{-1}}\] done clear
  View Solution play_arrow

• question_answer62)
  In a series LCR circuit, resistance \[R=10\Omega \] and the impedance \[Z=20\Omega .\] The phase difference between the current and the voltage is [KCET (Engg./Med.) 1999]
  A)
             \[{{30}^{o}}\]                        done clear
  B)
             \[{{45}^{o}}\] done clear
  C)
             \[{{60}^{o}}\]                        done clear
  D)
             \[{{90}^{o}}\] done clear
  View Solution play_arrow

• question_answer63)
  A series ac circuit consist of an inductor and a capacitor. The inductance and capacitance is respectively 1 henry and \[25\mu F.\] If the current is maximum in circuit then angular frequency will be                                                 [RPMT 1999]
  A)
             200 done clear
  B)
             100 done clear
  C)
             50   done clear
  D)
             200/2\[\pi \] done clear
  View Solution play_arrow

• question_answer64)
  An alternating e.m.f. of frequency \[v\,\left( =\frac{1}{2\pi \sqrt{LC}} \right)\] is applied to a series LCR circuit. For this frequency of the applied e.m.f.                                                                [Roorkee 1999]
  A)
             The circuit is at resonance and its impedance is made up only of a reactive part done clear
  B)
             The current in the circuit is in phase with the applied e.m.f. and the voltage across R equals this applied emf done clear
  C)
             The sum of the p.d.?s across the inductance and capacitance equals the applied e.m.f. which is \[{{180}^{o}}\] ahead of phase of the current in the circuit done clear
  D)
             The quality factor of the circuit is \[\omega L/R\] or \[1/\omega CR\] and this is a measure of the voltage magnification (produced by the circuit at resonance) as well as the sharpness of resonance of the circuit done clear
  View Solution play_arrow

• question_answer65)
  In the circuit shown below, the ac source has voltage \[V=20\cos (\omega t)\] volts with \[\omega \]= 2000 rad/sec. the amplitude of the current will be nearest to  [AMU (Engg.) 2000]
  A)
             \[2A\] done clear
  B)
             \[3.3A\] done clear
  C)
             \[2/\sqrt{5}A\] done clear
  D)
             \[\sqrt{5}A\] done clear
  View Solution play_arrow

• question_answer66)
  The value of the current through an inductance of \[1H\] and of negligible resistance, when connected through an ac source of 200 V and 50 Hz, is                                    [AFMC 2000]
  A)
             0.637 A                                    done clear
  B)
             1.637 A done clear
  C)
             2.637A                                     done clear
  D)
             3.637 A done clear
  View Solution play_arrow

• question_answer67)
  The quality factor of LCR circuit having resistance (R) and inductance (L) at resonance frequency (\[\omega \]) is given by [AFMC 2000; CBSE PMT 2000]
  A)
             \[\frac{\omega L}{R}\]      done clear
  B)
             \[\frac{R}{\omega L}\] done clear
  C)
             \[{{\left( \frac{\omega L}{R} \right)}^{1/2}}\]            done clear
  D)
             \[{{\left( \frac{\omega L}{R} \right)}^{2}}\] done clear
  View Solution play_arrow

• question_answer68)
  Power factor is maximum in an LCR circuit when [RPET 2000]
  A)
             \[{{X}_{L}}={{X}_{C}}\]      done clear
  B)
             \[R=0\] done clear
  C)
             \[{{X}_{L}}=0\]                     done clear
  D)
             \[{{X}_{C}}=0\] done clear
  View Solution play_arrow

• question_answer69)
  In an ac circuit the reactance of a coil is \[\sqrt{3}\] times its resistance, the phase difference between the voltage across the coil to the current through the coil will be   [KCET (Engg.) 2000]
  A)
             \[\pi /3\]                                 done clear
  B)
             \[\pi /2\] done clear
  C)
             \[\pi /4\]                                 done clear
  D)
             \[\pi /6\] done clear
  View Solution play_arrow

• question_answer70)
  The capacity of a pure capacitor is 1 farad. In dc circuits, its effective resistance will be                    [MP PMT 2000]
  A)
             Zero                                          done clear
  B)
             Infinite done clear
  C)
             1 ohm                                      done clear
  D)
             1/2 ohm done clear
  View Solution play_arrow

• question_answer71)
  In an ac circuit, the current lags behind the voltage by \[\pi /3\]. The components in the circuit are           [MP PMT 2000]
  A)
             R and L                                     done clear
  B)
             R and C done clear
  C)
             L and C                                     done clear
  D)
             Only R done clear
  View Solution play_arrow

• question_answer72)
  The reactance of a coil when used in the domestic ac power supply (220 volts, 50 cycles per second) is 50 ohms. The inductance of the coil is nearly         [MP PMT 2000]
  A)
             2.2 henry                                done clear
  B)
             0.22 henry done clear
  C)
             1.6 henry                                done clear
  D)
             0.16 henry done clear
  View Solution play_arrow

• question_answer73)
  In an ac circuit, the power factor                        [Roorkee 2000]
  A)
             Is zero when the circuit contains an ideal resistance only done clear
  B)
             Is unity when the circuit contains an ideal resistance only done clear
  C)
             Is zero when the circuit contains an ideal inductance only done clear
  D)
             Is unity when the circuit contains an ideal inductance only done clear
  View Solution play_arrow

• question_answer74)
  A resistance of 40 ohm and an inductance of 95.5 millihenry are connected in series in a 50 cycles/second ac circuit. The impedance of this combination is very nearly  [MP PET 2000]
  A)
             30 ohm                                    done clear
  B)
             40 ohm done clear
  C)
             50 ohm                                    done clear
  D)
             60 ohm done clear
  View Solution play_arrow

• question_answer75)
  For high frequency, a capacitor offers [CPMT 1999; CBSE PMT 1999; AFMC 2001; Pb. PET 2001; J & K CET 2004]
  A)
             More reactance                   done clear
  B)
             Less reactance done clear
  C)
             Zero reactance                     done clear
  D)
             Infinite reactance done clear
  View Solution play_arrow

• question_answer76)
  The coil of choke in a circuit                                      [AIIMS 2001]
  A)
             Increases the current done clear
  B)
             Decreases the current done clear
  C)
             Does not change the current done clear
  D)
             Has high resistance to dc circuit done clear
  View Solution play_arrow

• question_answer77)
  In a circuit, the current lags behind the voltage by a phase difference of \[\pi /2.\] The circuit contains which of the following                                                                          [AIIMS 2001]
  A)
             Only R                                      done clear
  B)
             Only L done clear
  C)
             Only C                                      done clear
  D)
             R and C done clear
  View Solution play_arrow

• question_answer78)
  The inductive reactance of an inductor of \[\frac{1}{\pi }\] henry at 50 Hz frequency is                                    [MP PET 2001, 02]
  A)
             \[\frac{50}{\pi }\]ohm       done clear
  B)
             \[\frac{\pi }{50}\] ohm done clear
  C)
             100 ohm                                  done clear
  D)
             50 ohm done clear
  View Solution play_arrow

• question_answer79)
  An oscillator circuit consists of an inductance of 0.5mH and a capacitor of 20\[\mu F\]. The resonant frequency of the circuit is nearly                                                         [Kerala PET 2002]
  A)
             15.92 Hz                                  done clear
  B)
             159.2 Hz done clear
  C)
             1592 Hz                                    done clear
  D)
             15910 Hz done clear
  View Solution play_arrow

• question_answer80)
  Reactance of a capacitor of capacitance \[C\mu F\] for ac frequency \[\frac{400}{\pi }\] Hz is \[25\Omega \]. The value C is [MH CET 2002]
  A)
             \[50\mu F\]                           done clear
  B)
             \[25\mu F\] done clear
  C)
             \[100\mu F\]                         done clear
  D)
             \[75\mu F\] done clear
  View Solution play_arrow

• question_answer81)
  The power factor of an ac circuit having resistance (R) and inductance (L) connected in series and an angular velocity \[\omega \] is                                           [AIEEE 2002; MP PET 2000]
  A)
             \[R/\omega L\]                    done clear
  B)
             \[R/{{({{R}^{2}}+{{\omega }^{2}}{{L}^{2}})}^{1/2}}\] done clear
  C)
             \[\omega L/R\]                    done clear
  D)
             \[R/{{({{R}^{2}}-{{\omega }^{2}}{{L}^{2}})}^{1/2}}\] done clear
  View Solution play_arrow

• question_answer82)
  A circuit has a resistance of \[11\Omega ,\] an inductive reactance of \[25\Omega \] and a capacitative resistance of \[18\Omega .\] It is connected to an ac source of 260V and 50Hz. The current through the circuit (in amperes) is                               [Kerala PMT 2002]
  A)
             11   done clear
  B)
             15 done clear
  C)
             18   done clear
  D)
             20 done clear
  View Solution play_arrow

• question_answer83)
  A 0.7 henry inductor is connected across a 120V ? 60 Hz ac source. The current in the inductor will be very nearly [MP PMT 2002]
  A)
             4.55 amp                                done clear
  B)
             0.355 amp done clear
  C)
             0.455 amp                              done clear
  D)
             3.55 amp done clear
  View Solution play_arrow

• question_answer84)
  There is a \[5\Omega \] resistance in an ac, circuit. Inductance of 0.1H is connected with it in series. If equation of ac e.m.f. is \[5\sin 50t\] then the phase difference between current and e.m.f. is                                  [RPET 2003]
  A)
             \[\frac{\pi }{2}\]                  done clear
  B)
             \[\frac{\pi }{6}\] done clear
  C)
             \[\frac{\pi }{4}\]                  done clear
  D)
             0 done clear
  View Solution play_arrow

• question_answer85)
  An inductor of inductance L and resistor of resistance R are joined in series and connected by a source of frequency \[\omega \]. Power dissipated in the circuit is [AIEEE 2002; RPET 2003]
  A)
             \[\frac{({{R}^{2}}+{{\omega }^{2}}{{L}^{2}})}{V}\]   done clear
  B)
             \[\frac{{{V}^{2}}R}{({{R}^{2}}+{{\omega }^{2}}{{L}^{2}})}\] done clear
  C)
             \[\frac{V}{({{R}^{2}}+{{\omega }^{2}}{{L}^{2}})}\]   done clear
  D)
             \[\frac{\sqrt{{{R}^{2}}+{{\omega }^{2}}{{L}^{2}}}}{{{V}^{2}}}\] done clear
  View Solution play_arrow

• question_answer86)
  In a ac circuit of capacitance the current from potential is  [CPMT 2003]
  A)
             Forward done clear
  B)
             Backward done clear
  C)
             Both are in the same phase done clear
  D)
             None of these done clear
  View Solution play_arrow

• question_answer87)
  A coil of 200W resistance and 1.0 H inductance is connected to an ac source of frequency \[200/2\pi \,Hz.\] Phase angle between potential and current will be            [MP PMT 2003]
  A)
             30o done clear
  B)
             90o done clear
  C)
             45o done clear
  D)
             0o done clear
  View Solution play_arrow

• question_answer88)
  In a LCR circuit the pd between the terminals of the inductance is 60 V, between the terminals of the capacitor is 30V and that between the terminals of resistance is 40V. the supply voltage will be equal to ??         [KCET 2004]
  A)
             50 V                                          done clear
  B)
             70 V done clear
  C)
             130 V                                        done clear
  D)
             10 V done clear
  View Solution play_arrow

• question_answer89)
  Radio frequency choke uses core of                     [AFMC 2004]
  A)
             Air  done clear
  B)
             Iron done clear
  C)
             Air and iron                            done clear
  D)
             None of these done clear
  View Solution play_arrow

• question_answer90)
  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       [AIEEE 2004]
  A)
             4L   done clear
  B)
             2L done clear
  C)
             L/2 done clear
  D)
             L/4 done clear
  View Solution play_arrow

• question_answer91)
  In an LCR series ac circuit, the voltage across each of the components, L, C and R is 50V. the voltage across the LC combination will be                                                       [AIEEE 2004]
  A)
             50V                                           done clear
  B)
             \[50\sqrt{2}\,V\] done clear
  C)
             100V                                         done clear
  D)
             0 V (zero) done clear
  View Solution play_arrow

• question_answer92)
  A coil has L = 0.04 H and \[R=12\,\Omega \]. When it is connected to 220V, 50Hz supply the current flowing through the coil, in amperes is                                         [Kerala PMT 2004]
  A)
             10.7                                           done clear
  B)
             11.7 done clear
  C)
             14.7                                           done clear
  D)
             12.7 done clear
  View Solution play_arrow

• question_answer93)
  The current in series LCR circuit will be maximum when w is [Kerala PMT 2004]
  A)
             As large as possible done clear
  B)
             Equal o natural frequency of LCR system done clear
  C)
             \[\sqrt{LC}\] done clear
  D)
             \[\sqrt{1/LC}\] done clear
  View Solution play_arrow

• question_answer94)
  An inductor L and a capacitor C are connected in the circuit as shown in the figure. The frequency of the power supply is equal to the resonant frequency of the circuit. Which ammeter will read zero ampere                                [DCE 2002]
  A)
             \[{{A}_{1}}\]                          done clear
  B)
             \[{{A}_{2}}\] done clear
  C)
             \[{{A}_{3}}\]                          done clear
  D)
             None of these done clear
  View Solution play_arrow

• question_answer95)
  Which of the following components of a LCR circuit, with ac supply, dissipates energy                                     [DCE 2004]
  A)
             L      done clear
  B)
             R done clear
  C)
             C     done clear
  D)
             All of these done clear
  View Solution play_arrow

• question_answer96)
  In a circuit \[L,\,C\text{  and  }R\]are connected in series with an alternating voltage source of frequency \[f\]. The current leads the voltage by 45°. The value of \[C\] is [CBSE PMT 2005]
  A)
             \[\frac{1}{2\pi f(2\pi fL+R)}\] done clear
  B)
             \[\frac{1}{\pi f(2\pi fL+R)}\] done clear
  C)
             \[\frac{1}{2\pi f(2\pi fL-R)}\]  done clear
  D)
             \[\frac{1}{\pi f(2\pi fL-R)}\] done clear
  View Solution play_arrow

• question_answer97)
  In an A.C. circuit the current                                     [CPMT 2005]
  A)
             Always leads the voltage         done clear
  B)
             Always lags behind the voltage                                                      done clear
  C)
             Is always in phase with the voltage                                 done clear
  D)
             May lead or lag behind or be in phase with the voltage done clear
  View Solution play_arrow

• question_answer98)
  For the series LCR circuit shown in the figure, what is the resonance frequency and the amplitude of the current at the resonating frequency                                   [Kerala PET 2005]
  A)
             \[2500\,rad-{{s}^{-1}}\] and \[5\sqrt{2}\,A\]              done clear
  B)
             \[2500\,rad-{{s}^{-1}}\] and \[5A\]                                 done clear
  C)
             \[2500\,rad-{{s}^{-1}}\] and \[\frac{5}{\sqrt{2}}A\] done clear
  D)
             \[25\,rad-{{s}^{-1}}\] and \[5\sqrt{2}\,A\] done clear
  View Solution play_arrow