Explore topic-wise MCQs in Electric Circuits.

This section includes 72 Mcqs, each offering curated multiple-choice questions to sharpen your Electric Circuits knowledge and support exam preparation. Choose a topic below to get started.

1.

A series RLC circuit consisting of R = 10 ohms, XL = 20 ohms and Xc = 20 ohms is connected across an ac supply of 100 V (rms). The magnitude and phase angle (with reference to supply voltage) of the voltage across the inductive coil are respectively

A. 100 V, 90
B. 100 V, 90
C. 200 V, 90
D. 200 V, 90
Answer» E.
2.

A 3 V dc supply with an internal resistance of 2 Ω supplies a passive non-linear resistance characterized by the relation VNL = I2 NL. The power dissipated in the non-linear resistance is

A. 1.0 W
B. 1.5 W
C. 2.5 W
D. 3.0 W
Answer» B. 1.5 W
3.

The Thevenin s equivalent of a circuit operating at = 5 rad/s, has Voc = 3.71 15.9 V and Z0 = 2.38 j 0.667 Ω . At this frequency, the minimal realization of the Thevenin s impedance will have a

A. resistor and a capacitor and an inductor
B. resistor and a capacitor
C. resistor and an inductor
D. capacitor and an inductor
Answer» C. resistor and an inductor
4.

An average-reading digital multimeter reads 10 V when fed with a triangular wave, symmetric about the time-axis. For the same input an rmsreading meter will read

A. 20
B. 10
Answer» B. 10
5.

A coil of 300 turns is wound on a non-magnetic core having a mean circumference of 300 mm and a cross-sectional area of 300 mm2. The inductance of the coil corresponding to a magnetizing current of 3A will be (Given that 0 = 4 10 7 H/m)

A. 37.68 H
B. 113.04 H
C. 37.68 mH
D. 113.04 mH
Answer» C. 37.68 mH
6.

A capacitor consists of two metal plates each 500 500 mm2 and spaced 6 mm apart. The space between the metal plates is filled with a glass plate of 4 mm thickness and a layer of paper of 2 mm thickness. The relative permittivities of the glass and paper are 8 and 2 respectively. Neglecting the fringing effect, the capacitance will be (Given that 0 = 8.85 10 12 F/m)

A. 983.33 pF
B. 1475 pF
C. 6637.5 pF
D. 9956.25 pF
Answer» C. 6637.5 pF
7.

Divergence of the vector field V (x, y, z) = (x cos xy + y) i + (y cos xy) j + (sin z2 + x2 + y2) k is

A. 2z cos z
B. sin xy + 2z cos z
C.
D. x sin xy cos z
E. none of these
Answer» B. sin xy + 2z cos z
8.

Two point charges Q1 = 10 C and Q2 = 20 C are placed at coordinates (1, 1, 0) and ( 1, 1, 0) respect ively. The total electric flux passing through a plane z = 20 will be

A. 7.5 C
B. 13.5 C
C. 15.0 C
D. 22.5 C
Answer» D. 22.5 C
9.

Consider the following statements with reference to the equation
p
t

1. This is a point form of the continuity equation
2. Divergence of current density is equal to the decrease of charge per unit volume per unit at every point
3. This is Max well's divergence equation
4. This represents the conservation of charge Select the correct answer:

A. Only 2 and 4 are true
B. 1, 2 and 3 are true
C. 2, 3 and 4 are true
D. 1, 2 and 4 are true
Answer» E.
10.

An incandescent lamp is marked 40W, 240V. If resistance at room temperature (26 C) is 120 Ω and temperature coefficient of resistance is 4.5 10 3/ C , then its ON state filament temperature in C is approximately ___________.

A. 1171
B. 2471
C. 1417
D. All of the above
Answer» C. 1417
11.

Current I1, I2 and I3 meet at a junction (node) in a circuit. All currents are marked as entering the node. If I1 = 6 sin ( t) mA and I2 = 8 cos ( t) mA, then I 3 will be

A. 10 cos ( t + 36.87) mA
B. 14 cos ( t + 36.87) mA
C. 14 sin ( t + 36.87) mA
D. 10 cos ( t + 36.87) mA
Answer» E.
12.

The maximum value of mutual inductance of two inductively coupled coils with selfinductance, L1 = 49 mH and L2 = 81 mH is

A. 130 mH
B. 63 mH
C. 32 mH
D. 3969 mH
Answer» C. 32 mH
13.

Divergence of the three-dimensional radial vector field r is

A. 3
B. 1 / r
Answer» B. 1 / r
14.

The driving point impedance Z(s) =
s + 2
s + 2

The system is initially at rest. For a voltage signal of unit step, the current i (t) through the impedance Z is given by

A. 2 - e
B. 3 - 2 e
Answer» D.
15.

After closing the switch S at t = 0, the current i (t) at any instant t in the network shown in the given figure will be

A. 10 + 10 e
B.
C. 10 10 e
D. 10 + 10 e
E. 10 10 e
Answer» E. 10 10 e
16.

Consider a function f =
1
r , where r is distance from origin and r is unit vector.
r2
, The divergence of this function over a sphere of radius R, which includes origin is.

A. 0
B. 2
C. 4
D. R .
Answer» D. R .
17.

In an unbalanced three phase system, phase current Ia = 1 ( 90 ) pu, negative sequence current Ib2 = 4 ( 150 )pu, zero sequence current IC0 = 3 90 pu. The magnitude of phase current Ib in pu is

A. 1.00
B. 7.81
C. 11.53
D. 13.00
Answer» D. 13.00
18.

A series RLC circuit s observed at two frequencies. At 1 = 1 k rad/s, we note that source voltage V1 = 100 0 V results in current I1 = 0.03 31 A. At 2 = 2 krad/s, the source volt age V2 = 100 0 V results in a current I2 = 2 0 A. The closest values for R, L, C out of the following options are

A. R = 50 Ω ; L = 25mH ; C =10 F;
B. R = 50 Ω ; L =10mH ; C = 25 F;
C. R = 50 Ω ; L = 50mH ; C = 5 F;
D. R = 50 Ω ; L = 5mH ; C = 50 F;
Answer» C. R = 50 Ω ; L = 50mH ; C = 5 F;
19.

The system function H(s) =
1
s + 1

For an input signal cos t, the steady state response is

A. cos t
Answer» B.
20.

A series LCR circuit consisting of R = 10 ohms [XL] = 20 ohms is connected across an a.c. supply of 200 V rms. The rms voltage across the capacitor is

A. 200 90 V
B. 200 + 90 V
C. 400 + 90 V
D. 400 90 V
Answer» E.
21.

In respect of the 2-port network shown in the given figure, admittance parameters are :
Y11 = 8 mho, Y12 = Y21 = 6 mho and Y22 = 6 mho. The values of YA, YB and YC (in units of mho) will be respectively

A. 2, 6 and 6
B. 2, 6 and 0
C. 2, 0 and 6
D. 2, 6 and 8
Answer» D. 2, 6 and 8
22.

A two-port network is defined by the relations I1 = 2V1 + V2, I2 = 2V1 + 3V2 Then z12 is

A. 2 Ω
B. 1 Ω
Answer» E.
23.

A battery charger can drive a current of 5 A into a 1 ohm resistance connected at its output teminals. If it is able to charge an ideal 2 V battery at 7 A rate, then its Thevenin s equivalent will be

A. 7.5 V in series with 0.5 ohm
B. 12 V in series with 1.5 ohms
C. 7.5 V in parallel with 0.5 ohm
D. 1.25 V in parallel with 1.5 ohms
Answer» C. 7.5 V in parallel with 0.5 ohm
24.

H ow many 200W/220V incandescent lamps connected in series would consume the same total power as a single 100W/220V incandescent lamp?

A. not possible
B. 4
C. 3
D. 2
Answer» E.
25.

A series RLC circuit consisting of R = 10 ohms, X

A. 100 V, 90
B. 100 V, 90
C. 200 V, 90
D. 200 V, 90
Answer» E.
26.

The number of independent loops for a network with n nodes and b branch is

A. n 1
B. b n
C. b n + 1
D. independent of the number of nodes
Answer» D. independent of the number of nodes
27.

A two terminal black box contains one of the R.L.C. elements. The black box is connected to a 220 volts A.C. supply. The current through the source is I. When a capacitance of 0.1F is inserted in the series between the source and the box, the current through the source is 2I. The element is

A. a resistance
B. an inductance
C. a capacitance of 0.5F
D. it is not possible to determine the element.
Answer» C. a capacitance of 0.5F
28.

The maximum value of mutual inductance of two inductively coupled coils with selfinductance, L

A. 130 mH
B. 63 mH
C. 32 mH
D. 3969 mH
Answer» C. 32 mH
29.

Two incandescent light bulbs of 40 W and 60W rating are connected in series across the mains. Then

A. the bulbs together consume 100 W
B. the bulbs together consume 50 W
C. the 60 W bulb glows brighter
D. the 40 bulb glows brighter
Answer» E.
30.

Current I

A. 10 cos ( t + 36.87) mA
B. 14 cos ( t + 36.87) mA
C. 14 sin ( t + 36.87) mA
D. 10 cos ( t + 36.87) mA
Answer» E.
31.

If the number of branches in a network is B, the number of nodes is N and the number of dependent loops is L, then the number of independent node equations will be

A. N + L 1
B. B 1
C. B N
D.
E. N 1
Answer» E. N 1
32.

A connected network of N > 2 nodes has at most one branch directly connecting any pair of nodes. The graph of the network

A. must have at least N branches for one or more closed paths to exist
B. can have an unlimited number of branches
C. can only have at most N branches
D. can have a minimum number of branches not decided by N.
Answer» E.
33.

A certain network consists of two ideal voltage sources and a large number of ideal resistors. The power consumed in one of the resistor is 4 W when either of the two sources is active and the other is replaced by a short circuit. The power consumed by the same resistor when both the sources are simultaneously active would be

A. zero or 16 W
B. 4 W or 8 W
C. zero or 8 W
D. 8 W or 16 W
Answer» D. 8 W or 16 W
34.

A load that has a resistance of 10 ohms is to be connected to a supply that has a constant voltage of 120 volts. If it is desired that the currrent to the load be varied from 3 to 5 amperes, what are the resistance and the current rating of the series rheostat that permit this variation?

A. 30 ohms, 5A
B. 10 ohms, 10A
C. 20 ohms, 10A
D. 20 ohms, 10A
Answer» B. 10 ohms, 10A
35.

The system function H(s) =
1
s + 1

A. <table><tr><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>1</center></td><td rowspan="2">cos </td><td rowspan="2"><img src="https://www.indiabix.com/_files/images/data-interpretation/common/15-sym-oparen-h1.gif"></td><td rowspan="2">t - </td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center> </center></td><td rowspan="2"><img src="https://www.indiabix.com/_files/images/data-interpretation/common/15-sym-cparen-h1.gif"></td><td rowspan="2"> </td></tr><tr><td style="text-align: center;"> <span style=" text-decoration: overline;">2</span></td><td style="text-align: center;">4</td></tr></table>
B. cos t
C. <table><tr><td rowspan="2">cos </td><td rowspan="2"><img src="https://www.indiabix.com/_files/images/data-interpretation/common/15-sym-oparen-h1.gif"></td><td rowspan="2">1 - </td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center> </center></td><td rowspan="2"><img src="https://www.indiabix.com/_files/images/data-interpretation/common/15-sym-cparen-h1.gif"></td><td rowspan="2"> </td></tr><tr><td style="text-align: center;">4</td></tr></table>
D. <table><tr><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>1</center></td><td rowspan="2">cos t</td></tr><tr><td style="text-align: center;"> <span style=" text-decoration: overline;">2</span></td></tr></table>
Answer» B. cos t
36.

In respect of the 2-port network shown in the given figure, admittance parameters are :

A. 2, 6 and 6
B. 2, 6 and 0
C. 2, 0 and 6
D. 2, 6 and 8
Answer» D. 2, 6 and 8
37.

An ideal transformer has turns ratio of 2 : 1. Considering high voltage side as port 1 and low voltage side as port 2, then transmission line parameters of transformer will be

A. <table><tr><td rowspan="2"><img src="https://www.indiabix.com/_files/images/data-interpretation/common/15-sym-obracket-h1.gif"></td><td>0</td><td></td><td></td><td>-2</td><td rowspan="2"><img src="https://www.indiabix.com/_files/images/data-interpretation/common/15-sym-cbracket-h1.gif"></td></tr><tr><td>0.5</td><td></td><td></td><td>0</td></tr></table>
B. <table><tr><td rowspan="2"><img src="https://www.indiabix.com/_files/images/data-interpretation/common/15-sym-obracket-h1.gif"></td><td>-2</td><td></td><td></td><td>0</td><td rowspan="2"><img src="https://www.indiabix.com/_files/images/data-interpretation/common/15-sym-cbracket-h1.gif"></td></tr><tr><td>0</td><td></td><td></td><td>-0.5</td></tr></table>
C. <table><tr><td rowspan="2"><img src="https://www.indiabix.com/_files/images/data-interpretation/common/15-sym-obracket-h1.gif"></td><td>2</td><td></td><td></td><td>0</td><td rowspan="2"><img src="https://www.indiabix.com/_files/images/data-interpretation/common/15-sym-cbracket-h1.gif"></td></tr><tr><td>0</td><td></td><td></td><td>-0.5</td></tr></table>
D. <table><tr><td rowspan="2"><img src="https://www.indiabix.com/_files/images/data-interpretation/common/15-sym-obracket-h1.gif"></td><td>0.5</td><td></td><td></td><td>0</td><td rowspan="2"><img src="https://www.indiabix.com/_files/images/data-interpretation/common/15-sym-cbracket-h1.gif"></td></tr><tr><td>0</td><td></td><td></td><td>2</td></tr></table>
Answer» D. <table><tr><td rowspan="2"><img src="https://www.indiabix.com/_files/images/data-interpretation/common/15-sym-obracket-h1.gif"></td><td>0.5</td><td></td><td></td><td>0</td><td rowspan="2"><img src="https://www.indiabix.com/_files/images/data-interpretation/common/15-sym-cbracket-h1.gif"></td></tr><tr><td>0</td><td></td><td></td><td>2</td></tr></table>
38.

Two coils having equal resistance but different inductances are connected in series. the time constant of the series combination is the

A. sum of the time constants of the individual coils
B. average of the time constants of individual coils
C. geometric mean of the time constants of the individual coils
D. product of the time constants of the individual coils
Answer» C. geometric mean of the time constants of the individual coils
39.

With the usual notations, a two-port resistive network satisfies the condition A = D =
3
B =
4
C
23

A. <table><tr><td rowspan="2"></td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>5</center></td><td rowspan="2"> </td></tr><tr><td style="text-align: center;">3</td></tr></table>
B. <table><tr><td rowspan="2"></td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>4</center></td><td rowspan="2"> </td></tr><tr><td style="text-align: center;">3</td></tr></table>
C. <table><tr><td rowspan="2"></td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>4</center></td><td rowspan="2"> </td></tr><tr><td style="text-align: center;">3</td></tr></table>
D. <table><tr><td rowspan="2"></td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>1</center></td><td rowspan="2"> </td></tr><tr><td style="text-align: center;">3</td></tr></table>
Answer» C. <table><tr><td rowspan="2"></td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>4</center></td><td rowspan="2"> </td></tr><tr><td style="text-align: center;">3</td></tr></table>
40.

A two-port network is defined by the relations I

A. 2 &ohm;
B. 1 &ohm;
C. <table><tr><td rowspan="2">-</td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>1</center></td><td rowspan="2"> &amp;ohm;</td></tr><tr><td style="text-align: center;">2</td></tr></table>
D. <table><tr><td rowspan="2"></td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>1</center></td><td rowspan="2"> &amp;ohm;</td></tr><tr><td style="text-align: center;">4</td></tr></table>
Answer» E.
41.

Five cells are connected in series in a row and then four such rows are connected in parallel to feed the current to a resistive load of 1.25 Ω . Each cell has emf of 1.5 V with internal resistance of 0.2 Ω . The current through the load will be _____ .

A. 1 A
B. 5 A
C. 15 A
D. None of the above
Answer» C. 15 A
42.

When two coupled coils of equal self-inductance are connected in series in one way the net inductance is 12 mH, and when they are connected in the other way, the net inductance is 4 mH. The maxiumum value of net inductance when they are connected in parallel in a suitable way is _________ mH

A. 3 mH
B. 5 mH
C. 9 mH
D. 10 mH
Answer» B. 5 mH
43.

A 35 V source is connected to a series circuit at 600 ohms and R as shown. If a voltmeter at internal resistance 1.2 kilo ohms is connected across 600 ohm resistor it reads 5 V. The value of R is ______k Ω .

A. 1.4 k&ohm;
B. 2.0 k&ohm;
C. 2.4 k&ohm;
D. None of these
Answer» D. None of these
44.

The energy stored in the magnetic field at a solenoid 30 cm long and 3 cm diameter wound with 1000 turns of wire carrying a current at 10 A, is ________ Joules

A. 0.148 or 0.15 Joules
B. 11.148 or 11.2 Joules
C. 10.120 or 10.15 Joules
D. None of the above
Answer» B. 11.148 or 11.2 Joules
45.

At a certain current, the energy stored in iron cored coil is 1000 J and its copper loss is 2000 W. The time constant (in seconds) of the coil is_____

A. 0
B. 1
C. 2
D. 3
Answer» C. 2
46.

A resistance R Ω and inductance of L H are connected across 240 V, Hz supply. Power dissipated in the circuit is 300 W and the voltage across R is 100 V. In order to improve the power fact or to unity, the capacitor that is to be connect ed in series should have a val ue of _______ F

A. 11.5 F.
B. 13.7 F.
C. 12.5 F.
D. 43.7 F.
Answer» E.
47.

Two coils in differential connection have self inductance of 2 mH and 4 mH and a mutual inductance of 0.15 mH. The equivalent inductance of the combination is _____ mH

A. 1.7 mH
B. 3.0 mH
C. 5.7 mH
D. 1.7 mH
Answer» D. 1.7 mH
48.

The Thevenin s equivalent of a circuit operating at = 5 rad/s, has V

A. resistor and a capacitor and an inductor
B. resistor and a capacitor
C. resistor and an inductor
D. capacitor and an inductor
Answer» C. resistor and an inductor
49.

Two point charges Q

A. 7.5 C
B. 13.5 C
C. 15.0 C
D. 22.5 C
Answer» D. 22.5 C
50.

A 3 V dc supply with an internal resistance of 2 Ω supplies a passive non-linear resistance characterized by the relation V

A. 1.0 W
B. 1.5 W
C. 2.5 W
D. 3.0 W
Answer» B. 1.5 W