-
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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
View Solution play_arrow
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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