Electromagnetic Induction — DPP 2

20 NEET questions from Electromagnetic Induction, with answers and explanations. Attempt it as a timed test to get scoring, accuracy breakdown and mistake tracking.

Attempt this test free 20 questions · 30 minutes · +80 marks
1
An inductance coil have the time constant 4 sec, if it is cut into two equal parts and connected parallel then new time constant of the circuit :-
  1. A 4 sec
  2. B 2 sec
  3. C 1 sec
  4. D 0.5 sec
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Correct answer: A

Electromagnetic Induction – NEET-20192
2
When a current changes from 2 A to 4 A in 0.05 sec. in a coil, induced emf is 8 V. The self-inductance of the coil is :-
  1. A 0.1 H
  2. B 0.2 H
  3. C 0.4 H
  4. D 0.8 H
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Correct answer: B

Electromagnetic Induction – NEET-20226
3
Pure inductors each of inductance 3 H are connected as shown. The equivalent induction of the circuit is :-
Electromagnetic Induction – NEET-20220
  1. A 1 H
  2. B 2 H
  3. C 3 H
  4. D 9 H
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Correct answer: A

In parallel combination
$\frac{1}{\mathrm{~L}}=\frac{1}{\mathrm{~L}_{1}}+\frac{1}{\mathrm{~L}_{2}}+\frac{1}{\mathrm{~L}_{3}}=\frac{1}{3}+\frac{1}{3}+\frac{1}{3}=\frac{3}{3}=1 \mathrm{H}$
4
Two conducting coils are placed co-axially now a cell is connected in one coil then they will :-
  1. A attract to each other
  2. B repel to each other
  3. C both (A) & (B)
  4. D they will not experience any force
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Correct answer: B

5
In the circuit shown in the figure, what is the value of $\mathrm { I } _ { 1 }$ just after pressing the key K?
Electromagnetic Induction – NEET-20219
  1. A $\frac { 5 } { 7 } \mathrm {~A}$
  2. B $\frac { 5 } { 11 } \mathrm {~A}$
  3. C 1 A
  4. D None of the above
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Correct answer: A

Electromagnetic Induction – NEET-20219
6
Which statement is correct from following-
(a) Inductor store energy in the form of magnetic field
(b) Capacitor store energy in the form of electric field
(c) Inductor store energy in the form of electric and magnetic field both
(d) Capacitor store energy in the form of electric and magnetic field both
  1. A a, b
  2. B a, c
  3. C b, d
  4. D b, c
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Correct answer: A

7
A cylindrical iron core supports N turns. If a current I produces a magnetic flux φ across the core's cross section, then the magnetic energy is :-
  1. A I $\phi$
  2. B $\frac { 1 } { 2 } \mathrm { I } \phi$
  3. C $\frac { I ^ { 2 } \phi } { 2 }$
  4. D $\mathrm { I } ^ { 2 } \phi$
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Correct answer: B

Electromagnetic Induction – NEET-20222
8
A constant current I is maintained in a solenoid. Which of the following quantities will increase if an iron rod is inserted into the solenoid along its axis?
(a) Magnetic field at the centre
(b) Magnetic flux linked with the solenoid
(c) Self-inductance of the solenoid
(d) Rate of Joule heating
  1. A a, b, c
  2. B c, d
  3. C a, b
  4. D Only b
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Correct answer: A

9
A coil of resistance 10 Ω and an inductance 5 H is connected to a 100 V battery. The energy stored in the coil is :-
  1. A 125 erg
  2. B 125 J
  3. C 250 erg
  4. D 250 J
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Correct answer: D

$\mathrm{U}=\frac{1}{2} \mathrm{LI}^{2}$, where $\mathrm{I}_{0}=\frac{\mathrm{E}}{\mathrm{R}}$
10
An inductance L and a resistance R are joined to a battery. After some time, the battery is disconnected, but L and R remain connected to the closed circuit. The current strength will be reduced to 37% of its initial value in:
  1. A RL sec
  2. B R/L sec
  3. C L/R sec
  4. D 1/LR sec
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Correct answer: C

11
If a current of 2 A give rise a magnetic flux of $5 \times 10 ^ { - 5 }$ weber/turn through a coil having 100 turns, then the magnetic energy stored in the medium surrounding by the coil is :-
  1. A 5 joule
  2. B $5 \times 10 ^ { - 7 }$ joule
  3. C $5 \times 10 ^ { - 3 }$ joule
  4. D 0.5 joule
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Correct answer: C

Electromagnetic Induction – NEET-20194
12
Energy is stored in the choke coil in the form of:-
  1. A Heat
  2. B Electric field
  3. C Magnetic field
  4. D Electro-magnetic field
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Correct answer: C

13
An ideal coil of 10 H is connected in series with a resistance of 5 Ω and a battery of 5 V. 2 seconds after the connection is made, the current flowing in amperes in the circuit is:-
  1. A e
  2. B e - 1
  3. C $\left( 1 - e ^ { - 1 } \right)$
  4. D (1 - e)
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Correct answer: C

Electromagnetic Induction – NEET-20235
14
During 0.1 s current in a coil increases from 1 A to 1.5 A . If inductance of this coil is $60 \mu \mathrm { H }$, induced current in external resistance of $600 \mu \Omega$ is :-
  1. A 1 A
  2. B 4/3 A
  3. C 2/3 A
  4. D 1/2 A
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Correct answer: D

Electromagnetic Induction – NEET-20218
15
A coil having an area of $2 \mathrm {~m} ^ { 2 }$ is placed in a magnetic field which changes from 1 Weber $/ \mathrm { m } ^ { 2 }$ to 4 Weber $/ \mathrm { m } ^ { 2 }$ in 2 seconds. The e.m.f. induced in the coil will be :-
  1. A 4 volt
  2. B 3 volt
  3. C 2 volt
  4. D 1 volt
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Correct answer: B

$\mathrm{e}=\mathrm{A} \frac{\Delta \mathrm{B}}{\Delta \mathrm{t}}=2\left(\frac{4-1}{2}\right)=3 \mathrm{volt}$
16
The time constant of an inductance coil is $2.0 \times 10 ^ { - 3 } \mathrm {~s}$. When a 90 Ω resistance is joined in series, the time constant becomes $0.5 \times 10 ^ { - 3 } \mathrm {~s}$. The inductance and resistance of the coil are :-
  1. A $30 \mathrm { mH } ; 30 \Omega$
  2. B $30 \mathrm { mH } ; 60 \Omega$
  3. C $60 \mathrm { mH } ; 30 \Omega$
  4. D $60 \mathrm { mH } ; 60 \Omega$
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Correct answer: C

Electromagnetic Induction – NEET-20221
17
One coil of resistance 40 Ω is connected to a galvanometer of 160 Ω resistance. The coil has radius 6 mm and turns 100. This coil is placed between the poles of a magnet such that magnetic field is perpendicular to coil. If coil is dragged out then the charge through the galvanometer is 32 μC. The magnetic field is:-
  1. A 6.55 T
  2. B 5.66 T
  3. C 0.655 T
  4. D 0.566 T
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Correct answer: D

$\begin{array}{l}\mathrm{q}=\frac{\Delta \phi}{\mathrm{R}} \Rightarrow \mathrm{q}=\frac{\mathrm{NBA}}{\mathrm{R}} \\ \mathrm{B}=\frac{\mathrm{qR}}{\mathrm{NA}}=\frac{32 \times 10^{-6} \times 200}{100 \times \pi\left(6 \times 10^{-3}\right)^{2}}=0.566 \mathrm{~T}\end{array}$
18
An LR circuit with a battery is connected at t = 0. Which of the following quantities is not zero just after the connection :-
(a) Current in circuit
(b) Magnetic potential energy in the inductor
(c) Power delivered by the battery
(d) Emf induced in the inductor
  1. A a, b
  2. B a, c
  3. C c, d
  4. D Only d
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Correct answer: D

19
When current in a coil is reduced from 2A to 1 A in 1 ms, the induced emf is 5 V. The inductance of coil is :
  1. A 5 H
  2. B 5000 H
  3. C 5 mH
  4. D 50 H
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Correct answer: C

$\begin{aligned} \mathrm{e} & =\frac{\mathrm{LdI}}{\mathrm{dt}} \Rightarrow \mathrm{L}=\frac{\mathrm{e}}{(\mathrm{dI} / \mathrm{dt})}=\frac{5}{\left(1 / 10^{-3}\right)} \\ & =5 \times 10^{-3}=5 \mathrm{mH}\end{aligned}$
20
An e.m.f. of 12 V is induced in a given coil when the current in it changes at the rate of 48 A/min. The inductance of the coil is:
  1. A 0.5 henry
  2. B 15 henry
  3. C 1.5 henry
  4. D 9.6 henry
Show answer

Correct answer: B

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