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Year: 2024
Topic: Electromagnetic induction
1.
A 10μF capacitor is connected to a 210V, 50Hz source as shown in figure. The peak current in the circuit is nearly (π = 3.14) :
(1).
0.58 A
(2).
0.93 A
(3).
1.20 A
(4).
0.35 A

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Year: 2023
Topic: Electromagnetic induction
2.
The net magnetic flux through any closed surface is
(1).
Positive
(2).
Infinity
(3).
Negative
(4).
Zero

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Year: 2022
Topic: Electromagnetic induction
3.
The peak voltage of the ac source is equal to
(1).
The value of voltage supplied to the circuit
(2).
The rms value of the ac source
(3).
\(\displaystyle \sqrt{2}\) times the rms value of the ac source
(4).
\(\displaystyle \frac{1}{\sqrt{2}}\) times the rms value of the ac source

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Year: 2024
Topic: Electromagnetic induction
4.
In an ideal transformer, the turns ratio is \(\frac{N_P}{N_S} = \frac{1}{2}\). The ratio \(V_S : V_P\) is equal to (the symbols carry their usual meaning) :
(1).
1 : 2
(2).
2 : 1
(3).
1 : 1
(4).
1 : 4

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Year: 2023
Topic: Electromagnetic induction
5.
The magnetic energy stored in an inductor of inductance 4μH carrying a current of 2A is
(1).
4 mJ
(2).
8 mJ
(3).
8 μJ
(4).
4 μJ

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Year: 2023
Topic: Electromagnetic induction
6.
In a series LCR circuit, the inductance L is 10mH,capacitance C is 1μF and resistance R is 100Ω. The frequency at which resonance occurs is
(1).
15.9 kHz
(2).
1.59 rad∕ s
(3).
1.59 kHz
(4).
15.9 rad∕ s

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Year: 2023
Topic: Electromagnetic induction
7.
A 12V, 60W lamp is connected to the secondary of a step-down transformer, whose primary is connected to ac mains of 220V. Assuming the transformer to be ideal, what is the current in the primary winding?
(1).
2.7 A
(2).
3.7 A
(3).
0.37 A
(4).
0.27 A

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Year: 2022
Topic: Electromagnetic induction
8.
A square loop of side 1m and resistance 1Ω is placed in a magnetic field of 0.5 T . If the plane of loop is perpendicular to the direction of magnetic field, the magnetic flux through the loop is
(1).
2 weber
(2).
0.5 weber
(3).
1 weber
(4).
Zero weber

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Year: 2022
Topic: Electromagnetic induction
9.
A series LCR circuit with inductance 10 H , capacitance 10 μF , resistance 50 Ω is connected to an ac source of voltage, V = 200 sin(100t) volt. If the resonant frequency of the LCR circuit is v0 and the frequency of the ac source is v, then
(1).
\(\displaystyle v_0\, =\, v\, =\, 50\) Hz
(2).
\(\displaystyle v_0\, =\, v\, =\, \frac{50}{\pi}\) Hz
(3).
\(\displaystyle v_0\, =\, \frac{50}{\pi}\) Hz, \(v\, =\, 50\) Hz
(4).
\(\displaystyle v\, =\, 100\)Hz; \(\displaystyle v_0\, =\, \frac{100}{\pi}\) Hz

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Year: 2022
Topic: Electromagnetic induction
10.
A big circular coil of 1000 turns and average radius 10 m is rotating about its horizontal diameter at 2 rad−1. If the vertical component of earth's magnetic field at that place is 2 × 10−5T and electrical resistance of the coil is 12.56Ω, then the maximum induced current in the coil will be
(1).
0.25 A
(2).
1.5 A
(3).
1 A
(4).
2 A

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Year: 2021
Topic: Electromagnetic induction
11.
A step down transformer connected to an ac mains supply of 220 V is made to operate at 11 V, 44 W lamp. Ignoring power losses in the transformer, what is the current in the primary circuit?
(1).
0.2 A
(2).
0.4 A
(3).
2 A
(4).
4 A

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Year: 2021
Topic: Electromagnetic induction
12.
Two conducting circular loops of radii R1 and R2 are placed in the same plane with their centres coinciding. If R1 > R2, the mutual inductance M between them will be directly proportional to
(1).
\(\displaystyle \frac{R_1}{R_2}\)
(2).
\(\displaystyle \frac{R_2}{R_1}\)
(3).
\(\displaystyle \frac{R_1^2}{R_2}\)
(4).
\(\displaystyle \frac{R_2^2}{R_1}\)

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Year: 2020
Topic: Electromagnetic induction
13.
A series LCR circuit is connected to an ac voltage source. When L is removed from the circuit, the phase difference between current and voltage is \(\pi /3\). If instead C is removed from the circuit, the phase difference is again \(\pi /3\) between current and voltage. The power factor of the circuit is:
(1).
0.5
(2).
1.0
(3).
-1.0
(4).
zero

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Year: 2019
Topic: Electromagnetic induction
14.
In which of the following devices, the eddy current effect is not used?
(1).
electric heater
(2).
induction furnace
(3).
magnetic braking in train
(4).
electromagnet

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Year: 2019
Topic: Electromagnetic induction
15.
A 800 turn coil of effective area 0.05m2 is kept perpendicular to a magnetic field 5 × 10−5 T. When the plane of the coil is rotated by 90∘ around any of its coplanar axis in 0.1 s, the emf induced in the coil will be
(1).
0.02 V
(2).
2 V
(3).
0.2 V
(4).
2 × 10−3 V

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Year: 2018
Topic: Electromagnetic induction
16.
The magnetic potential energy stored in a certain inductor is 25 mJ , when the current in the inductor is 60 mA. This inductor is of inductance
(1).
0.138 H
(2).
138.88 H
(3).
1.389 H
(4).
13.89 H

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Year: 2018
Topic: Electromagnetic induction
17.
An inductor 20 mH , a capacitor 100 μF and a resistor 50 Ω are connected in series across a source of emf,
V = 10 sin 314 t. The power loss in the circuit is
(1).
0.79 W
(2).
0.43 W
(3).
2.74 W
(4).
1.13 W

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Year: 2017
Topic: Electromagnetic induction
18.
A long solenoid of diameter 0.1 m has 2 × 104 turns per metre. At the centre of the solenoid, a coil of 100 turns and radius 0.01 m is placed with its axis coinciding with the solenoid axis. The current in the solenoid reduces at a constant rate to 0 A from 4 A in 0.05 s. If the resistance of the coil is 10π2Ω, the total charge flowing through the coil during this time is
(1).
16 μC
(2).
32 μC
(3).
16 πμC
(4).
32 π μC

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Year: 2017
Topic: Electromagnetic induction
19.
Figure shows a circuit that contains three identical resistors with resistance R = 9.0Ω each, two identical inductors with inductance L =2.0 mH each, and an ideal battery with emf ε = 18V . The current i through the battery just after the switch closed is
(1).
0.2 A
(2).
none of the above
(3).
0 A
(4).
2 mA

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Year: 2016
Topic: Electromagnetic induction
20.
An inductor 20 mH, a capacitor 50 μF and a resistor 40 Ω are connected in series across a source of emf
\(V\, =\, 10\,sin\,340\,t\). The power loss in A.C. circuit is
(1).
0.76 W
(2).
0.89 W
(3).
0.51 W
(4).
0.67 W

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Year: 2016
Topic: Electromagnetic induction
21.
A small signal voltage V (t) = V0 sin ωt is applied across an ideal capacitor C
(1).
Current I(t) is in phase with voltage V(t).
(2).
Current I(t) leads voltage V(t) by 180°.
(3).
Current I(t), lags voltage V(t) by 90°
(4).
Over a full cycle the capacitor C does not consume any energy from the voltage source

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Year: 2016
Topic: Electromagnetic induction
22.
A long solenoid has 1000 turns. When a current of 4 A flows through it, the magnetic flux linked with each turn of the solenoid is 4 × 10 −3 Wb. The self-inductance of the solenoid is
(1).
2 H
(2).
1 H
(3).
4 H
(4).
3 H

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