JEE Main & Advanced Physics Electro Magnetic Induction Question Bank

done Static EMI Total Questions - 108

• question_answer1)
  The back e.m.f. induced in a coil, when current changes from 1 ampere to zero in one milli‑second, is 4 volts, the self-inductance of the coil is                                   [MP PET/PMT 1988]
  A)
             1 H done clear
  B)
             4 H done clear
  C)
             \[{{10}^{-3}}\] H                  done clear
  D)
             \[4\times {{10}^{-3}}\] H done clear
  View Solution play_arrow

• question_answer2)
  An e.m.f. of 5 volt is produced by a self inductance, when the current changes at a steady rate from 3 A to 2 A in 1 millisecond. The value of self inductance is [CPMT 1982; MP PMT 1991; CBSE PMT 1993; AFMC 2002]
  A)
             Zero                                          done clear
  B)
             5 H done clear
  C)
             5000 H                                      done clear
  D)
             5 mH done clear
  View Solution play_arrow

• question_answer3)
  A 50 mH coil carries a current of 2 ampere. The energy stored in joules is               [MP PET/PMT 1988; MP PET 2005]
  A)
             1     done clear
  B)
             0.1 done clear
  C)
             0.05                                           done clear
  D)
             0.5 done clear
  View Solution play_arrow

• question_answer4)
  The current passing through a choke coil of 5 henry is decreasing at the rate of 2 ampere/sec. The e.m.f. developing across the coil is                                      [CPMT 1982; MP PMT 1990; AIIMS 1997; MP PET 1999]
  A)
             10 V                                          done clear
  B)
             ? 10 V done clear
  C)
             2.5 V                                         done clear
  D)
             ? 2.5 V done clear
  View Solution play_arrow

• question_answer5)
  Average energy stored in a pure inductance L when a current i flows through it, is                                            [MP PET/PMT 1988]
  A)
             \[L{{i}^{2}}\]                          done clear
  B)
             \[2L{{i}^{2}}\] done clear
  C)
             \[\frac{L{{i}^{2}}}{4}\]       done clear
  D)
             \[\frac{L{{i}^{2}}}{2}\] done clear
  View Solution play_arrow

• question_answer6)
  A solenoid has 2000 turns wound over a length of 0.30 metre. The area of its cross-section is \[1.2\times {{10}^{-3}}{{m}^{2}}\]. Around its central section, a coil of 300 turns is wound. If an initial current of 2 A in the solenoid is reversed in 0.25 sec, then the e.m.f. induced in the coil is [NCERT 1982; MP PMT 2003]
  A)
             \[6\times {{10}^{-4}}V\]   done clear
  B)
             \[4.8\times {{10}^{-3}}V\] done clear
  C)
             \[6\times {{10}^{-2}}V\]   done clear
  D)
             48 mV done clear
  View Solution play_arrow

• question_answer7)
  A coil is wound as a transformer of rectangular cross-section. If all the linear dimensions of the transformer are increased by a factor 2 and the number of turns per unit length of the coil remain the same, the self  inductance increased by a factor of                                             [AIIMS 1980]
  A)
              16  done clear
  B)
             12 done clear
  C)
              8    done clear
  D)
             4 done clear
  View Solution play_arrow

• question_answer8)
  Two coils of self-inductance \[{{L}_{1}}\] and \[{{L}_{2}}\] are placed closer to each other so that total flux in one coil is completely linked with other. If \[M\] is mutual inductance between them, then [DCE 2002]
  A)
             \[M={{L}_{1}}{{L}_{2}}\]   done clear
  B)
             \[M={{L}_{1}}/{{L}_{2}}\] done clear
  C)
             \[M=\sqrt{{{L}_{1}}{{L}_{2}}}\]                                         done clear
  D)
             \[M={{({{L}_{1}}{{L}_{2}})}^{2}}\] done clear
  View Solution play_arrow

• question_answer9)
  The equivalent quantity of mass in electricity is
  A)
              Charge                                    done clear
  B)
             Potential done clear
  C)
              Inductance                           done clear
  D)
             Current            done clear
  View Solution play_arrow

• question_answer10)
   The momentum in mechanics is expressed as \[m\times v\]. The analogous expression in electricity is  [MP PMT 2003]
  A)
             \[I\times Q\]                         done clear
  B)
             \[I\times V\] done clear
  C)
             \[L\times I\]                          done clear
  D)
             \[3.75\times {{10}^{-2}}\,N\] done clear
  View Solution play_arrow

• question_answer11)
  In what form is the energy stored in an inductor or A coil of inductance L is carrying a steady current i. What is the nature of its stored energy                [CBSE PMT 1990, 92;  MP PMT 1996, 2000, 02; Kerala PMT 2002]
  A)
              Magnetic                               done clear
  B)
              Electrical done clear
  C)
              Both magnetic and electrical done clear
  D)
              Heat done clear
  View Solution play_arrow

• question_answer12)
  The coefficient of self inductance of a solenoid is 0.18 mH. If a crode of soft iron of relative permeability 900 is inserted, then the coefficient of self inductance will become nearly
  A)
              5.4 mH                                    done clear
  B)
             162 mH done clear
  C)
              0.006 mH                               done clear
  D)
             0.0002 mH done clear
  View Solution play_arrow

• question_answer13)
  In a transformer, the coefficient of mutual inductance between the primary and the secondary coil is 0.2 henry. When the current changes by 5 ampere/second in the primary, the induced e.m.f. in the secondary will be [MP PMT 1989]
  A)
              5 V done clear
  B)
             1 V done clear
  C)
              25 V                                         done clear
  D)
             10 V done clear
  View Solution play_arrow

• question_answer14)
  When the current in a coil changes from 8 ampere to 2 ampere in \[3\times {{10}^{-2}}\]second, the e.m.f. induced in the coil is \[2\ volt\]. The self-inductance of the coil (in millihenry) is        [MNR 1991; UP SEAT 2000; Pb PET 2004]
  A)
              1    done clear
  B)
             5 done clear
  C)
              20  done clear
  D)
             10 done clear
  View Solution play_arrow

• question_answer15)
  The mutual inductance between two coils is 1.25 henry. If the current in the primary changes at the rate of 80 ampere/second, then the induced e.m.f. in the secondary is  [MP PET 1990]
  A)
              12.5 V                                      done clear
  B)
             64.0 V done clear
  C)
              0.016 V                                   done clear
  D)
             100.0 V done clear
  View Solution play_arrow

• question_answer16)
  A coil of wire of a certain radius has 600 turns and a self inductance of 108 mH. The self inductance of a 2nd  similar coil of 500 turns will be                                                   [MP PMT 1990]
  A)
             74 mH                                      done clear
  B)
             75 mH done clear
  C)
             76 mH                                      done clear
  D)
             77 mH done clear
  View Solution play_arrow

• question_answer17)
   When the number of turns in a coil is doubled without any change in the length of the coil, its self inductance becomes [MP PMT 1986; CBSE PMT 1992; Pb PET 2000]
  A)
             Four times                             done clear
  B)
             Doubled done clear
  C)
             Halved                                     done clear
  D)
             Unchanged done clear
  View Solution play_arrow

• question_answer18)
   The average e.m.f. induced in a coil in which the current changes from 2 ampere to 4 ampere in 0.05 second is 8 volt. What is the self-inductance of the coil? [NCERT 1984; CPMT 1997; MP PMT 1999, 2003; UPSEAT 2000; RPMT 2000; Pb. PMT 2002; RPET 2003; DPMT 2005]
  A)
             0.1 H                                         done clear
  B)
             0.2 H done clear
  C)
             0.4 H                                         done clear
  D)
             0.8 H done clear
  View Solution play_arrow

• question_answer19)
  If a current of 3.0 amperes flowing in the primary coil is reduced to zero in 0.001 second, then the induced e.m.f. in the secondary coil is 15000 volts. The mutual inductance between the two coils is                                      [MP PMT 1989, 91]
  A)
             0.5 henry                                done clear
  B)
             5 henry done clear
  C)
             1.5 henry                                done clear
  D)
             10 henry done clear
  View Solution play_arrow

• question_answer20)
  An e.m.f. of 12 volts is induced in a given coil when the current in it changes at the rate of 48 amperes per minute. The self inductance of the coil is              [MP PMT 2000]
  A)
             0.25 henry                              done clear
  B)
             15 henry done clear
  C)
             1.5 henry                                done clear
  D)
             9.6 henry done clear
  View Solution play_arrow

• question_answer21)
  A closely wound coil of 100 turns and area of cross-section \[1\ c{{m}^{2}}\] has a coefficient of self-induction 1 mH. The magnetic induction in the centre of the core of the coil when a current of 2A flows in it, will be                          [MP PET 1992]
  A)
             \[0.022\ Wb{{m}^{-2}}\]  done clear
  B)
             \[0.4\ Wb\ {{m}^{-2}}\] done clear
  C)
             \[0.8\ Wb\ {{m}^{-2}}\]    done clear
  D)
             \[1\ Wb\ {{m}^{-2}}\]   done clear
  View Solution play_arrow

• question_answer22)
   Two circuits have coefficient of mutual induction of 0.09 henry. Average e.m.f. induced in the secondary by a change of current from 0 to 20 ampere in 0.006 second in the primary will be                                       [MP PET 1992]
  A)
             120 V                                        done clear
  B)
             80 V done clear
  C)
             200 V                                        done clear
  D)
             300 V done clear
  View Solution play_arrow

• question_answer23)
  In the following circuit, the bulb will become suddenly bright if                                                  [CBSE PMT 1989]
  A)
             Contact is made or broken done clear
  B)
             Contact is made done clear
  C)
             Contact is broken done clear
  D)
             Won't become bright at all done clear
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• question_answer24)
   Two pure inductors each of self inductance L are connected in parallel but are well separated from each other. The total inductance is  [MP PET 1991; Pb. PMT 1999; BHU 1998, 05]
  A)
             \[2L\]                                       done clear
  B)
             L done clear
  C)
             \[\frac{L}{2}\]                       done clear
  D)
             \[\frac{L}{4}\] done clear
  View Solution play_arrow

• question_answer25)
  A coil and a bulb are connected in series with a dc source, a soft iron core is then inserted in the coil. Then [MP PMT 1990; RPET 2001]
  A)
             Intensity of the bulb remains the same done clear
  B)
             Intensity of the bulb decreases done clear
  C)
             Intensity of the bulb increases done clear
  D)
             The bulb ceases to glow done clear
  View Solution play_arrow

• question_answer26)
  Self-induction of a solenoid is                             [MP PMT 1993]
  A)
             Directly proportional to current flowing through the coil done clear
  B)
             Directly proportional to its length done clear
  C)
             Directly proportional to area of cross-section done clear
  D)
             Inversely proportional to area of cross-section done clear
  View Solution play_arrow

• question_answer27)
  Mutual inductance of two coils can be increased by [MP PET 1994]
  A)
             Decreasing the number of turns in the coils done clear
  B)
             Increasing the number of turns in the coils done clear
  C)
             Winding the coils on wooden core done clear
  D)
             None of the above done clear
  View Solution play_arrow

• question_answer28)
  The self-inductance of a coil is 5 henry, a current of 1 amp change to 2 amp within 5 second through the coil. The value of induced e.m.f. will be                     [MP PET 1994;  Similar MP PET/PMT 1998; CBSE PMT 1990]
  A)
             10 volt                                      done clear
  B)
             0.10 volt done clear
  C)
             1.0 volt                                    done clear
  D)
             100 volt done clear
  View Solution play_arrow

• question_answer29)
  The unit of inductance is                     [MP PMT 1994, 95;  MP PET 1997; MP PMT/PET 1998; RPET 2001]
  A)
             Volt/ampere                         done clear
  B)
             Joule/ampere done clear
  C)
             Volt-sec/ampere                 done clear
  D)
             Volt-ampere/sec done clear
  View Solution play_arrow

• question_answer30)
  The current flowing in a coil of self inductance 0.4 mH is increased by 250 mA in 0.1 sec. The e.m.f. induced will be [MP PMT 1994]
  A)
             + 1 V                                         done clear
  B)
             ? 1 V done clear
  C)
             + 1 mV                                     done clear
  D)
             ? 1 mV done clear
  View Solution play_arrow

• question_answer31)
  5 cm long solenoid having 10 ohm resistance and 5 mH inductance is joined to a 10 volt battery. At steady state the current through the solenoid in ampere will be [MP PET 1995]
  A)
             5     done clear
  B)
             1 done clear
  C)
             2     done clear
  D)
             Zero done clear
  View Solution play_arrow

• question_answer32)
  When current in a coil changes to 2 ampere from 8 ampere in \[3\times {{10}^{-3}}\,\sec ond\], the e.m.f. induced in the coil is 2 volt. The self inductance of the coil in millihenry is [MP PET 1995]
  A)
             1     done clear
  B)
             5 done clear
  C)
             20   done clear
  D)
             10 done clear
  View Solution play_arrow

• question_answer33)
  An ideal coil of 10 henry is joined in series with a resistance of 5 ohm and a battery of 5 volt.  2 second after joining, the current flowing in ampere in the circuit will be [MP PET 1995]
  A)
             \[{{e}^{-1}}\]                        done clear
  B)
             \[(1-{{e}^{-1}})\] done clear
  C)
             \[(1-e)\]                                  done clear
  D)
             e done clear
  View Solution play_arrow

• question_answer34)
  The number of turns of primary and secondary coils of a transformer are 5 and 10 respectively and the mutual inductance of the transformer is 25 henry. Now the number of turns in the primary and secondary of the transformer are made 10 and 5 respectively. The mutual inductance of the transformer in henry will be                                          [MP PET 1995]
  A)
             6.25                                           done clear
  B)
             12.5 done clear
  C)
             25   done clear
  D)
             50 done clear
  View Solution play_arrow

• question_answer35)
  The inductance of a coil is \[60\,\mu H\]. A current in this coil increases from 1.0 A to 1.5 A in 0.1 second. The magnitude of the induced e.m.f. is                                          [MP PMT 1995]
  A)
             \[60\times {{10}^{-6}}\,V\]     done clear
  B)
             \[300\times {{10}^{-4}}\,V\] done clear
  C)
             \[30\times {{10}^{-4}}\,V\]     done clear
  D)
             \[3\times {{10}^{-4}}\,V\] done clear
  View Solution play_arrow

• question_answer36)
  A circular coil of radius 5 cm has 500 turns of a wire. The approximate value of the coefficient of self induction of the coil will be                                          [MP PET 1996; Pb PET 2000]
  A)
             25 millihenry                          done clear
  B)
             \[25\times {{10}^{-3}}\]millihenry done clear
  C)
             \[50\times {{10}^{-3}}\]millihenry                                   done clear
  D)
             \[50\times {{10}^{-3}}\]henry done clear
  View Solution play_arrow

• question_answer37)
  An e.m.f. of 100 millivolts is induced in a coil when the current in another nearby coil becomes 10 ampere from zero in 0.1 second. The coefficient of mutual induction between the two coils will be     [MP PET 1996; Kerala PMT 2004]
  A)
             1 millihenry                            done clear
  B)
             10 millihenry done clear
  C)
             100 millihenry                       done clear
  D)
             1000 millihenry done clear
  View Solution play_arrow

• question_answer38)
  In a coil of self inductance 0.5 henry, the current varies at a constant rate from zero to 10 amperes in 2 seconds. The e.m.f. generated in the coil is                              [MP PMT 1996]
  A)
             10 volts                                    done clear
  B)
             5 volts done clear
  C)
             2.5 volts                                  done clear
  D)
             1.25 volts done clear
  View Solution play_arrow

• question_answer39)
  A coil of self-inductance 50 henry is joined to the terminals of a battery of e.m.f. 2 volts through a resistance of 10 ohm and a steady current is flowing through the circuit. If the battery is now disconnected, the time in which the current will decay to 1/e of its steady value is               [MP PMT 1996]
  A)
             500 seconds                           done clear
  B)
             50 seconds done clear
  C)
             5 seconds                               done clear
  D)
             0.5 seconds done clear
  View Solution play_arrow

• question_answer40)
  The self inductance of a solenoid of length L, area of cross-section A and having N turns is  [MP PET 1997; MP PET 2003]
  A)
             \[\frac{{{\mu }_{0}}{{N}^{2}}A}{L}\]                               done clear
  B)
             \[\frac{{{\mu }_{0}}NA}{L}\] done clear
  C)
             \[{{\mu }_{0}}{{N}^{2}}LA\]   done clear
  D)
             \[{{\mu }_{0}}NAL\] done clear
  View Solution play_arrow

• question_answer41)
  The self inductance of a coil is L. Keeping the length and area same, the number of turns in the coil is increased to four times. The self inductance of the coil will now be [MP PMT 1997]
  A)
             \[\frac{1}{4}L\]                     done clear
  B)
             L done clear
  C)
             4 L  done clear
  D)
             16 L done clear
  View Solution play_arrow

• question_answer42)
  The mutual inductance between a primary and secondary circuits is 0.5 H. The resistances of the primary and the secondary circuits are 20 ohms and 5 ohms respectively. To generate a current of 0.4 A in the secondary, current in the primary must be changed at the rate of  [MP PMT 1997]
  A)
             4.0 A/s                                     done clear
  B)
             16.0 A/s done clear
  C)
             1.6 A/s                                     done clear
  D)
             8.0 A/s done clear
  View Solution play_arrow

• question_answer43)
  The energy stored in a 50 mH inductor carrying a current of 4 A will be                                    [MP PET 1999]
  A)
             0.4 J                                          done clear
  B)
             4.0 J done clear
  C)
             0.8 J                                          done clear
  D)
             0.04 J done clear
  View Solution play_arrow

• question_answer44)
  The average e.m.f. induced in a coil in which a current changes from 0 to 2 A in 0.05 s is 8 V. The self inductance of the coil is                                                           [CPMT 1999]
  A)
             0.1 H                                         done clear
  B)
             0.2 H done clear
  C)
             0.4 H                                         done clear
  D)
             0.8 H done clear
  View Solution play_arrow

• question_answer45)
  If the current is halved in a coil, then the energy stored is how much times the previous value    [CPMT 1999]
  A)
             \[\frac{1}{2}\]                       done clear
  B)
             \[\frac{1}{4}\] done clear
  C)
             2     done clear
  D)
             4 done clear
  View Solution play_arrow

• question_answer46)
  The SI unit of inductance, the henry, can be written as [IIT JEE 1998]
  A)
             Weber/ampere                    done clear
  B)
             Volt-second/ampere done clear
  C)
             Joule/(ampere)2                  done clear
  D)
             Ohm-second done clear
  View Solution play_arrow

• question_answer47)
  A varying current in a coil changes from 10 amp to zero in 0.5 sec. If average EMF is induced in the coil is 220 volts, the self-inductance of coil is [EAMCET 1994; MH CET (Med.) 1999]
  A)
             5 H done clear
  B)
             10 H done clear
  C)
             11 H                                          done clear
  D)
             12 H done clear
  View Solution play_arrow

• question_answer48)
  Which of the following is wrong statement        [AMU 1995]
  A)
             An emf can be induced between the ends of a straight conductor by moving it through a uniform magnetic field done clear
  B)
             The self-induced emf produced by changing current in a coil always tends to decrease the current done clear
  C)
             Inserting an iron core in a coil increases its coefficient of self induction done clear
  D)
             According to Lenz's law, the direction of the induced current is such that it opposes the flux change that causes it done clear
  View Solution play_arrow

• question_answer49)
  A coil has an inductance of 2.5 H and a resistance of 0.5 r. If the coil is suddenly connected across a 6.0 volt battery, then the time required for the current to rise 0.63 of its final value is                                       [AMU 1995]
  A)
             3.5 sec                                      done clear
  B)
             4.0 sec done clear
  C)
             4.5 sec                                      done clear
  D)
             5.0 sec done clear
  View Solution play_arrow

• question_answer50)
  When the number of turns and the length of the solenoid are doubled keeping the area of cross-section same, the inductance                                          [CBSE PMT 1993; MH CET 2000]
  A)
             Remains the same              done clear
  B)
             Is halved done clear
  C)
             Is doubled                              done clear
  D)
             Becomes four times done clear
  View Solution play_arrow

• question_answer51)
  A 100 mH coil carries a current of 1 ampere. Energy stored in its magnetic field is                [CBSE PMT 1992; KCET 1998]
  A)
             0.5 J                                          done clear
  B)
             1 J done clear
  C)
             0.05 J                                        done clear
  D)
             0.1 J done clear
  View Solution play_arrow

• question_answer52)
  The mutual inductance of an induction coil is \[5H\]. In the primary coil, the current reduces from \[5A\] to zero in \[{{10}^{-3}}s\]. What is the induced emf in the secondary coil   [RPET 1996]
  A)
             \[2500V\]                               done clear
  B)
             25000V done clear
  C)
             2510V                                       done clear
  D)
             Zero done clear
  View Solution play_arrow

• question_answer53)
  The self inductance of a straight conductor is     [KCET 1998]
  A)
             Zero                                          done clear
  B)
             Very large done clear
  C)
             Infinity                                     done clear
  D)
             Very small done clear
  View Solution play_arrow

• question_answer54)
  What is the coefficient of mutual inductance when the magnetic flux changes by \[2\times {{10}^{-2}}Wb\] and change in current is 0.01A                                       [BHU 1998; AIIMS 2002]
  A)
             2 henry                                    done clear
  B)
             3 henry done clear
  C)
             \[\frac{1}{2}\ henry\]        done clear
  D)
             Zero done clear
  View Solution play_arrow

• question_answer55)
  The current in a coil changes from 4 ampere to zero in 0.1 s. If the average e.m.f. induced is 100 volt, what is the self inductance of the coil                                                   [MNR 1998]
  A)
             \[2.5\ H\]                                done clear
  B)
             \[25\,H\] done clear
  C)
             \[400\ H\]                               done clear
  D)
             \[40\ H\] done clear
  View Solution play_arrow

• question_answer56)
  Pure inductance of 3.0 H is connected as shown below. The equivalent inductance of the circuit is [MNR 1998; AIEEE 2002]
  A)
             1 H done clear
  B)
             2 H done clear
  C)
             3 H done clear
  D)
             9 H done clear
  View Solution play_arrow

• question_answer57)
  A varying current at the rate of 3 A/s in a coil generates an e.m.f. of 8 mV in a nearby coil. The mutual inductance of the two coils is                                                            [Pb. PMT 2000]
  A)
             2.66 mH                                   done clear
  B)
             \[2.66\times {{10}^{-3}}\,mH\] done clear
  C)
             2.66 H                                       done clear
  D)
             0.266 H done clear
  View Solution play_arrow

• question_answer58)
  If a current of 10 A flows in one second through a coil, and the induced e.m.f. is 10 V, then the self-inductance of the coil is      [CPMT 2000; Pb. PMT 2001; MHCET 2003]
  A)
             \[\frac{2}{5}H\]                    done clear
  B)
             \[\frac{4}{5}H\] done clear
  C)
             \[\frac{5}{4}H\]                    done clear
  D)
             1 H done clear
  View Solution play_arrow

• question_answer59)
  The inductance of a closed-packed coil of 400 turns is 8 mH. A current of 5 mA is passed through it. The magnetic flux through each turn of the coil is        [Roorkee 2000]
  A)
             \[\frac{1}{4\pi }\,{{\mu }_{0}}Wb\]                                 done clear
  B)
             \[\frac{1}{2\pi }\] m0Wb done clear
  C)
             \[\frac{1}{3\pi }{{\mu }_{0}}Wb\]                                    done clear
  D)
             \[0.4\,{{\mu }_{0}}Wb\] done clear
  View Solution play_arrow

• question_answer60)
  When the current through a solenoid increases at a constant rate, the induced current                  [UPSEAT 2000]
  A)
             Is constant and is in the direction of the inducing current done clear
  B)
             Is a constant and is opposite to the direction of the inducing current done clear
  C)
             Increases with time and is in the direction of the inducing current done clear
  D)
             Increases with time and opposite to the direction of the inducing current done clear
  View Solution play_arrow

• question_answer61)
  If in a coil rate of change of area is 5 m2/milli second and current become 1 amp from 2 amp in \[2\times {{10}^{-3}}\,sec.\] If magnitude of field is 1 tesla then self inductance of the coil is [RPET 2000]
  A)
             2 H done clear
  B)
             5 H done clear
  C)
             20 H                                          done clear
  D)
             10 H done clear
  View Solution play_arrow

• question_answer62)
  The inductance of a solenoid 0.5 m long of cross-sectional area 20 cm2 and with 500 turns is         [AMU (Med.) 2000]
  A)
             12.5 mH                                   done clear
  B)
             1.25 mH done clear
  C)
             15.0 mH                                   done clear
  D)
             0.12 mH done clear
  View Solution play_arrow

• question_answer63)
  The equivalent inductance of two inductances is 2.4 henry when connected in parallel and 10 henry when connected in series. The difference between the two inductances is [MP PMT 2000]
  A)
             2 henry                                    done clear
  B)
             3 henry done clear
  C)
             4 henry                                    done clear
  D)
             5 henry done clear
  View Solution play_arrow

• question_answer64)
  An e.m.f. of 12 volt is produced in a coil when the current in it changes at the rate of 45 amp/minute. The inductance of the coil is                                                                   [MP PET 2000]
  A)
             0.25 henry                              done clear
  B)
             1.5 henry done clear
  C)
             9.6 henry                                done clear
  D)
             16.0 henry done clear
  View Solution play_arrow

• question_answer65)
  An average induced e.m.f. of 1V appears in a coil when the current in it is changed from 10A in one direction to 10 A in opposite direction in 0.5 sec. Self-inductance of the coil is  [CPMT 2001]
  A)
             25 mH                                      done clear
  B)
             50 mH done clear
  C)
             75 mH                                      done clear
  D)
             100 mH done clear
  View Solution play_arrow

• question_answer66)
  A coil of resistance 10 W and an inductance 5H is connected to a 100 volt battery. Then energy stored in the coil is [Pb. PMT 2001; CPMT 2002]
  A)
             125 erg                                    done clear
  B)
             125 J done clear
  C)
             250 erg                                    done clear
  D)
             250 J done clear
  View Solution play_arrow

• question_answer67)
  If a change in current of 0.01 A in one coil produces a change in magnetic flux of \[1.2\times {{10}^{-2}}Wb\] in the other coil, then the mutual inductance of the two coils in henries is [EAMCET 2001]
  A)
             0     done clear
  B)
             0.5 done clear
  C)
             1.2  done clear
  D)
             3 done clear
  View Solution play_arrow

• question_answer68)
  Energy stored in a coil of self inductance 40mH carrying a steady current of 2 A is                                               [Kerala (Engg.) 2001]
  A)
             0.8 J                                          done clear
  B)
             8 J done clear
  C)
             0.08 J                                        done clear
  D)
             80 J done clear
  View Solution play_arrow

• question_answer69)
  A solenoid of length l metre has self-inductance L henry. If number of turns are doubled, its self inductance [MP PMT 2001]
  A)
             Remains same                      done clear
  B)
             Becomes 2L henry done clear
  C)
             Becomes 4L henry              done clear
  D)
             Becomes \[\frac{L}{\sqrt{2}}\] henry done clear
  View Solution play_arrow

• question_answer70)
  Two coils A and B having turns 300 and 600 respectively are placed near each other, on passing a current of 3.0 ampere in A, the flux linked with A is \[1.2\times {{10}^{-4}}\,weber\] and with B it is \[9.0\times {{10}^{-5}}\,weber\]. The mutual inductance of the system is                                                                         [MP PMT 2001]
  A)
  \[2\times {{10}^{-5}}\,henry\]            done clear
  B)
  \[3\times {{10}^{-5}}\,henry\] done clear
  C)
  \[4\times {{10}^{-5}}\,henry\]              done clear
  D)
  \[6\times {{10}^{-5}}\,henry\] done clear
  View Solution play_arrow

• question_answer71)
  In a circular conducting coil, when current increases from 2 A to 18 A in 0.05 sec., the induced e.m.f. is 20 V. The self inductance of the coil is                                           [MP PET 2001]
  A)
             62.5 mH                                   done clear
  B)
             6.25 mH done clear
  C)
             50 mH                                      done clear
  D)
             None of these done clear
  View Solution play_arrow

• question_answer72)
  Find out the e.m.f. produced when the current changes from 0 to 1 A in 10 second, given L = 10 mH          [DCE 2001]
  A)
             1 V done clear
  B)
             1 mV done clear
  C)
             1 mV                                         done clear
  D)
             0.1 V done clear
  View Solution play_arrow

• question_answer73)
  Which of the following is not the unit of self inductance  [AMU (Med.) 2001]
  A)
             Weber/Ampere                    done clear
  B)
             Ohm-Second done clear
  C)
             Joule-Ampere                       done clear
  D)
             Joule Ampere?2 done clear
  View Solution play_arrow

• question_answer74)
  A coil of 100 turns carries a current of 5 mA and creates a magnetic flux of 10?5 weber. the inductance is [Orissa JEE 2002]
  A)
             0.2 mH                                     done clear
  B)
             2.0 mH done clear
  C)
             0.02 mH                                   done clear
  D)
             None of these done clear
  View Solution play_arrow

• question_answer75)
  In circular coil, when no. of turns is doubled and resistance becomes \[\frac{1}{4}th\] of initial, then inductance becomes [AIEEE 2002]
  A)
             4 times                                     done clear
  B)
             2 times done clear
  C)
             8 times                                     done clear
  D)
             No change done clear
  View Solution play_arrow

• question_answer76)
  The current in a coil of inductance 5 H decreases at the rate of 2 A/s. The induced e.m.f. is                           [MH CET 2002]
  A)
  2 V done clear
  B)
  5 V done clear
  C)
  10 V                                          done clear
  D)
  - 10 V done clear
  View Solution play_arrow

• question_answer77)
  The self-induced e.m.f. in a 0.1 H coil when the current in it is changing at the rate of 200 ampere/second  is                                                                                              [DPMT 2002]
  A)
             \[8\times {{10}^{-4}}\,V\]       done clear
  B)
             \[8\times {{10}^{-5}}\,V\] done clear
  C)
             \[20\,V\]                                 done clear
  D)
             \[125\,V\] done clear
  View Solution play_arrow

• question_answer78)
  Two circuits have mutual inductance of 0.1 H. What average e.m.f. is induced in one circuit when the current in the other circuit changes from 0 to 20 A in 0.02 s  [Kerala PET 2002]
  A)
             240 V                                        done clear
  B)
             230 V done clear
  C)
             100 V                                        done clear
  D)
             300 V done clear
  View Solution play_arrow

• question_answer79)
  An air core solenoid has 1000 turns and is one metre long. Its cross-sectional area is 10 cm2. Its self inductance is [JIPMER 2002]
  A)
             0.1256 mH                              done clear
  B)
             12.56 mH done clear
  C)
             1.256 mH                                done clear
  D)
             125.6 mH done clear
  View Solution play_arrow

• question_answer80)
  The coefficient of mutual inductance of two coils is 6 mH. If the current flowing in one is 2 ampere, then the induced e.m.f. in the second coil will be                                  [BVP 2003]
  A)
             3 mV                                         done clear
  B)
             2 mV done clear
  C)
             3 V done clear
  D)
             Zero done clear
  View Solution play_arrow

• question_answer81)
  An L-R circuit has a cell of e.m.f. E, which is switched on at time t = 0. The current in the circuit after a long time will be [MP PET 2003]
  A)
             Zero                                          done clear
  B)
             \[\frac{E}{R}\] done clear
  C)
             \[\frac{E}{L}\]                       done clear
  D)
             \[\frac{E}{\sqrt{{{L}^{2}}+{{R}^{2}}}}\] done clear
  View Solution play_arrow

• question_answer82)
  Two coils are placed close to each other. The mutual inductance of the pair of coils depends upon            [AIEEE 2003]
  A)
             The currents in the two coils done clear
  B)
             The rates at which currents are changing in the two coils done clear
  C)
             Relative position and orientation of the two coils done clear
  D)
             The materials of the wires of the coils done clear
  View Solution play_arrow

• question_answer83)
  When the current change from + 2A to ? 2A in 0.05 second, an e.m.f. of 8 V is induced in a coil. The coefficient of self-induction of the coil is                                                  [AIEEE 2003]
  A)
             0.1 H                                         done clear
  B)
             0.2 H done clear
  C)
             0.4 H                                         done clear
  D)
             0.8 H done clear
  View Solution play_arrow

• question_answer84)
  A coil resistance 20W and inductance 5H is connected with a 100V battery. Energy stored in the coil will be [MP PMT 2003]
  A)
             41.5 J                                        done clear
  B)
             62.50 J done clear
  C)
             125 J                                         done clear
  D)
             250 J done clear
  View Solution play_arrow

• question_answer85)
  Why the current does not rise immediately in a circuit containing inductance                                       [EAMCET 1994]
  A)
             Because of induced emf done clear
  B)
             Because of high voltage drop done clear
  C)
             Because of low power consumption done clear
  D)
             Because of Joule heating done clear
  View Solution play_arrow

• question_answer86)
  Two circular coils have their centres at the same point. The mutual inductance between them will be maximum when their axes                                                                     [MP PMT 2004]
  A)
             Are parallel to each other done clear
  B)
             Are at 60o to each other done clear
  C)
             Are at 45o to each other   done clear
  D)
             Are perpendicular to each other done clear
  View Solution play_arrow

• question_answer87)
  The current in a coil decreases from 1 A to 0.2 A. In 10sec. Calculate the coefficient of self inductance. If induced emf is 0.4 volt.                                                                         [BCECE 2004]
  A)
             5 H done clear
  B)
             3 H done clear
  C)
             4 H done clear
  D)
             2 H done clear
  View Solution play_arrow

• question_answer88)
  The current through choke coil increases form zero to 6A in 0.3 seconds and an induced e.m.f. of 30 V is produced. The inductance of the coil of choke is                       [MP PMT 2004]
  A)
             5 H done clear
  B)
             2.5 H done clear
  C)
             1.5 H                                         done clear
  D)
             2 H  done clear
  View Solution play_arrow

• question_answer89)
  The resistance and inductance of series circuit are \[5\Omega \] and   20H respectively. At the instant of closing the switch, the current is increasing at the rate 4A-s. The supply voltage is [MP PMT 2004]
  A)
             20 V                                          done clear
  B)
             80 V done clear
  C)
             120 V                                        done clear
  D)
             100 V  done clear
  View Solution play_arrow

• question_answer90)
  A coil of N = 100 turns carries a current I = 5 A and creates a magnetic flux \[\varphi ={{10}^{-5}}T{{m}^{-2}}\] per turn. The value of its inductance L will be                                                                         [UPSEAT 2004]
  A)
             0.05 mH                                   done clear
  B)
             0.10 mH done clear
  C)
             0.15 mH                                   done clear
  D)
             0.20 mH  done clear
  View Solution play_arrow

• question_answer91)
  Two identical induction coils each of inductance L joined in series are placed very close to each other such that the winding direction of one is exactly opposite to that of the other, what is the net inductance                        [DCE 2003]
  A)
             L2    done clear
  B)
             2L done clear
  C)
             L/2 done clear
  D)
             Zero done clear
  View Solution play_arrow

• question_answer92)
  If the current 30 A flowing in the primary coil is made zero in 0.1 sec. The emf induced in the secondary coil is 1.5 volt. The mutual inductance between the coil is     [Pb PMT 2003]
  A)
             0.05 H                                       done clear
  B)
             1.05 H done clear
  C)
             0.1 H                                         done clear
  D)
             0.2 H     done clear
  View Solution play_arrow

• question_answer93)
  Eddy currents are used in                                          [AFMC 2004]
  A)
             Induction furnace               done clear
  B)
             Electromagnetic brakes done clear
  C)
             Speedometers                     done clear
  D)
             All of these done clear
  View Solution play_arrow

• question_answer94)
  The adjoining figure shows two bulbs B1 and B2 resistor R and an inductor L. When the switch S is turned off  [CPMT 1989]
  A)
             Both B1 and B2 die out promptly done clear
  B)
             Both B1 and B2 die out with some delay done clear
  C)
             B1 dies out promptly but B2 with some delay done clear
  D)
             B2 dies out promptly but B1 with some delay done clear
  View Solution play_arrow

• question_answer95)
  In L-R circuit, for the case of increasing current, the magnitude of current can be calculated by using the formula [MP PET 1994]
  A)
             \[I={{I}_{0}}{{e}^{-Rt/L}}\]      done clear
  B)
             \[I={{I}_{0}}(1-{{e}^{-Rt/L}})\] done clear
  C)
             \[I={{I}_{0}}(1-{{e}^{Rt/L}})\]                                            done clear
  D)
             \[I={{I}_{0}}{{e}^{Rt/L}}\] done clear
  View Solution play_arrow

• question_answer96)
  An inductance L and a resistance R are first connected to a battery. After some time the battery is disconnected but L and R remain connected in a closed circuit. Then the current reduces to 37% of its initial value in                [MP PMT 1994]
  A)
             RL sec                                       done clear
  B)
             \[\frac{R}{L}sec\] done clear
  C)
             \[\frac{L}{R}sec\]                done clear
  D)
             \[\frac{1}{LR}sec\] done clear
  View Solution play_arrow

• question_answer97)
  In an LR-circuit, time constant is that time in which current grows from zero to the value (where \[{{I}_{0}}\] is the steady state current)                 [MP PMT/PET 1998; MP PET 2002]
  A)
             \[0.63\,{{I}_{0}}\]                done clear
  B)
             \[0.50\,{{I}_{0}}\] done clear
  C)
             \[0.37\,{{I}_{0}}\]                done clear
  D)
             \[{{I}_{0}}\] done clear
  View Solution play_arrow

• question_answer98)
  In the figure magnetic energy stored in the coil is                                             [RPET 2000]
  A)
             Zero                                          done clear
  B)
             Infinite done clear
  C)
             25 joules                                 done clear
  D)
             None of the above done clear
  View Solution play_arrow

• question_answer99)
  A capacitor is fully charged with a battery. Then the battery is removed and coil is connected with the capacitor in parallel, current varies as                            [RPET 2000; DCE 2000]
  A)
             Increases monotonically  done clear
  B)
             Decreases monotonically done clear
  C)
             Zero                                          done clear
  D)
             Oscillates indefinitely done clear
  View Solution play_arrow

• question_answer100)
  A coil of inductance 40 henry is connected in 0series with a resistance of 8 ohm and the combination is joined to the terminals of a 2 volt battery. The time constant of the circuit is                                                   [MP PET 2000]
  A)
             40 seconds                             done clear
  B)
             20 seconds done clear
  C)
             8 seconds                               done clear
  D)
             5 seconds done clear
  View Solution play_arrow

• question_answer101)
  A solenoid has an inductance of 60 henrys and a resistance of 30 ohms. If it is connected to a 100 volt battery, how long will it take for the current to reach \[\frac{e-1}{e}\approx 63.2%\] of its final value                                 [MP PET 2000]
  A)
             1 second                                 done clear
  B)
             2 seconds done clear
  C)
             e seconds                               done clear
  D)
             2e seconds done clear
  View Solution play_arrow

• question_answer102)
   An inductor, L a resistance R and two identical bulbs, \[{{B}_{1}}\] and \[{{B}_{2}}\] are connected to a battery through a switch S as shown in the figure. The resistance R is the same as that of the coil that makes L. Which of the following statements gives the correct description of the happenings when the switch S is closed                                                [AMU (Med.) 2002]
  A)
             The bulb B2 lights up earlier than B1 and finally both the bulbs shine equally bright done clear
  B)
             B1 light up earlier and finally both the bulbs acquire equal brightness done clear
  C)
             B2 lights up earlier and finally B1 shines brighter than B2 done clear
  D)
             B1 and B2 light up together with equal brightness all the time done clear
  View Solution play_arrow

• question_answer103)
  The time constant of an LR circuit represents the time in which the current in the circuit                [MP PMT 2002]
  A)
             Reaches a value equal to about 37% of its final value done clear
  B)
             Reaches a value equal to about 63% of its final value done clear
  C)
             Attains a constant value done clear
  D)
             Attains 50% of the constant value done clear
  View Solution play_arrow

• question_answer104)
  A LC circuit is in the state of resonance. If \[C=0.1\mu F\] and \[L=0.25\]henry. Neglecting ohmic resistance of circuit what is the frequency of oscillations  [BHU 2003; MP PMT 2005]
  A)
             1007 Hz                                    done clear
  B)
             100 Hz done clear
  C)
             109 Hz                                      done clear
  D)
             500 Hz done clear
  View Solution play_arrow

• question_answer105)
  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_answer106)
  A coil of inductance 300 mH and resistance \[2\Omega \] is connected to a source of voltage \[2V\]. The current reaches half of its steady state value in                                                                  [AIEEE 2005]
  A)
             0.15 s                                        done clear
  B)
             0.3 s done clear
  C)
             0.05 s                                        done clear
  D)
             0.1 s done clear
  View Solution play_arrow

• question_answer107)
  A coil having an inductance of 0.5 H carries a current which is uniformly varying from zero to 10 ampere in 2 second. The e.m.f. (in volts) generated in the coil is    [Kerala PET 2005]
  A)
             10   done clear
  B)
             5     done clear
  C)
             2.5 done clear
  D)
             1.25 done clear
  View Solution play_arrow

• question_answer108)
  The square root of the product of inductance and capacitance has the dimension of                        [KCET 2005]
  A)
             Length done clear
  B)
             Mass done clear
  C)
             Time done clear
  D)
             No dimension done clear
  View Solution play_arrow