Explore topic-wise MCQs in Network Theory.

This section includes 43 Mcqs, each offering curated multiple-choice questions to sharpen your Network Theory knowledge and support exam preparation. Choose a topic below to get started.

1.

A 10-μF capacitor in series with a 1-MΩ resistor is connected across a 100-V DC supply. The time constant of the circuit is ___________.

A. 0.1 s
B. 10 ms
C. 10 s
D. 100 s
Answer» D. 100 s
Discussion
2.

In the figure given below, the initial capacitor voltage is zero. Then after the switch is closed at t = 0, Calculate the final steady-state voltage across the capacitor:

A. 20 V
B. 10 V
C. 5 V
D. 0 V
Answer» C. 5 V
Discussion
3.

In the circuit shown below, the switch is closed at t = 0. The value of θ in degrees which will give the maximum value of DC offset of the current at the time of switching is

A. 60
B. -45
C. 90
D. -30
Answer» C. 90
Discussion
4.

For the given circuit, the switch remains closed for a long time and opens at t = 0 seconds. Assuming the ideal model for every device, find the steady-state magnitude of the voltage at the capacitor.

A. 1
B. 25
C. 50
D. 100
Answer» D. 100
Discussion
5.

In the circuit shown, the voltage source 4V has been applied for a long time before the switch opens at t = 0, the current Ir(0+) is

A. 4 mA
B. 3 mA
C. 1.33 mA
D. 1 mA
Answer» E.
Discussion
6.

In the circuit shown, the initial current I0 through the inductor is given in the figure. The initial value of the voltage across the inductor V0(0+) is

A. 12.5 V
B. 5.0 V
C. 10.0 V
D. 0.0 V
Answer» B. 5.0 V
Discussion
7.

A 20-mF capacitor is in series with a 150-ohm resistor. The combination is placed across a 40-V DC source. The time constant of the circuit is ________.

A. 8 s
B. 2.4 s
C. 6 s
D. 3 s
Answer» E.
Discussion
8.

In the given circuit, find the current I in the 3-kΩ resistor at time t = 2 sec.

A. 4 mA
B. 2 mA
C. 4 A
D. 2 A
Answer» C. 4 A
Discussion
9.

An 18 μF capacitor holding charge of Q coulomb is connected to the circuit at time t = 0 sec.The time at which the capacitor will be discharged to approximately Q/2.72 Coulombs will be:

A. 68 ms
B. 34 ms
C. 17 ms
D. 2.72 ms
Answer» B. 34 ms
Discussion
10.

During charging of the capacitor, the current actually drops to _________ percent of its initial maximum value.

A. 73
B. 42
C. 63
D. 37
Answer» E.
Discussion
11.

A 220 Ω resistor is in series with a 2.2 μF capacitor. The time constant is:

A. 48 μs
B. 480 μs
C. 2.42 μs
D. 242 μs
Answer» C. 2.42 μs
Discussion
12.

Consider the following RC circuit. The capacitor has an initial charge q0 such that it opposes the flow of charging current:The response of the circuit i(t) will be

A. \(\left( \frac{E}{R}-\frac{{{q}_{0}}}{RC} \right){{e}^{-\frac{t}{RC}}}\)
B. \(-\frac{{{q}_{0}}}{RC}{{e}^{-\frac{t}{RC}}}\)
C. \(\frac{E}{R}\;{e^{ - \frac{t}{{RC}}}}\;\)
D. \(\left( {\frac{E}{R} + \frac{{{q_0}}}{{RC}}} \right){e^{ - \frac{t}{{RC}}}}\)
Answer» B. \(-\frac{{{q}_{0}}}{RC}{{e}^{-\frac{t}{RC}}}\)
Discussion
13.

In the given circuit, the switch is closed at t = 0. Find the value of I.

A. 6A
B. -3A
C. 3A
D. -6A
Answer» E.
Discussion
14.

A coil having a resistance of 8 Ω and inductance of 2 H is switched across a 48 V DC supply. The time constant of the circuit and the final value of the current in the circuit, respectively are:

A. 0.4 and 24 A
B. 0.2 and 4.8 A
C. 0.25 and 8 A
D. 0.25 and 6 A
Answer» E.
Discussion
15.

In the given circuit what will the voltage be across R2 when after 25 μs the switch is moved to position 2?

A. 2.88 V
B. 5.9 V
C. 8.34 V
D. 14 V
Answer» C. 8.34 V
Discussion
16.

Find the inductor current after the switch closes in the circuit.

A. \(i\left( t \right) = 4\;\left( {1 + {e^{ - \frac{t}{5}}}} \right)\) mA, and t is in μs
B. \(i\left( t \right) = 4\;\left( {1 + {e^{ \frac{t}{5}}}} \right)\)mA, and t is in μs
C. \(i\left( t \right) = 4\;\left( {1 - {e^{ - \frac{t}{5}}}} \right)\) mA, and t is in μs
D. \(i\left( t \right) = 4\;\left( {1 - {e^{ \frac{t}{5}}}} \right)\) mA, and t is in μs
Answer» D. \(i\left( t \right) = 4\;\left( {1 - {e^{ \frac{t}{5}}}} \right)\) mA, and t is in μs
Discussion
17.

A 10-μF capacitor in series with a 1-MΩ resistor is connected across a 100-V DC supply. The initial rate of rise of voltage across the capacitor is _________.

A. 10 V/s
B. 0.01 V/s
C. 1 V/s
D. 0.1 V/s
Answer» B. 0.01 V/s
Discussion
18.

A series RL circuit is excited at t = 0 by closing a switch as shown in the figure. Assuming zero initial conditions, the value of \(\frac{{{d^2}i}}{{d{t^2}}}at\;t = {0^ + }\) is

A. V/L
B. -V/R
C. 0
D. -RV/L2
Answer» E.
Discussion
19.

For the R-L circuit shown, the current i(t) for unit step input voltage will rise to 0.63 in

A. 1 s
B. 2 s
C. 0.5 s
D. 1.5 s
Answer» D. 1.5 s
Discussion
20.

At t = 0+ an inductor with zero initial condition acts as a/an

A. short circuit with voltage reflected back
B. open circuit with current reflected back
C. open circuit with voltage reflected back
D. short circuit with current reflected back
Answer» C. open circuit with voltage reflected back
Discussion
21.

In an R-C circuit, when the switch S is closed, the response _________.

A. decays with time
B. rise with time
C. do not vary with time
D. first increases and then decreases
Answer» B. rise with time
Discussion
22.

At certain current, the energy stored in iron cored coil is 1000 J and its copper loss is 2000 W. The time constant is:

A. 0.25
B. 0.5
C. 1
D. 2
Answer» D. 2
Discussion
23.

By which of the following elements transients will not occur?

A. L
B. R
C. C
D. All of these
Answer» C. C
Discussion
24.

During capacitor charging, the voltage actually rises to _________ per cent of its _________ value.

A. 63.2, initial
B. 63.2, final
C. 37, initial
D. 37, final
Answer» C. 37, initial
Discussion
25.

In the circuit shown below, the switch, initially at position 1 for a long time, is changed to position 2 at t = 0.The current I through the inductor for t ≥ 0 is

A. I – e-20tA
B. I + e-20tA
C. I + 2e-20tA
D. 2 – e-20tA
Answer» E.
Discussion
26.

In the following circuit, switch K is throw from position A to position B at time t = 0, the current having previously reached its steady-state:The response of the circuit i (t) will be

A. 5e­-5t
B. 4e­-5t
C. 3e­-5t
D. e­-5t
Answer» E.
Discussion
27.

In the circuit shown the switch is opened at t = 0 after having been closed for a long time. Current through the resistor for t > 0 is given by:

A. 4 e-50t
B. 5 e-50t
C. 4 e-120t
D. 3 e-120t
Answer» D. 3 e-120t
Discussion
28.

In a series RL circuit the value of inductance is 1 Henry and resistance is 10 ohms. If 100 V DC is applied to the circuit at t = 0, what is the value of current at 0.1 sec?

A. 10 A
B. 1 A
C. 6.3 A
D. 3.7 A
Answer» D. 3.7 A
Discussion
29.

After the first time constant, a transient current has changed by _________ % leaving _________ % remaining.

A. 63.2, 36.8
B. 36.8, 63.2
C. 13.5, 86.5
D. 86.5, 13.5
Answer» B. 36.8, 63.2
Discussion
30.

During discharging of a capacitor of C = 1000 μF through a resistance of 1 kΩ applied with 50 V, the voltage at time constant is

A. 18.35 V
B. 50 V
C. 45 V
D. Zero
Answer» B. 50 V
Discussion
31.

A unit-step voltage is applied at t = 0 to a series R-L circuit with zero initial condition. Then

A. it is possible for the current to be oscillatory
B. the voltage across the resistor at t = 0+ is zero
C. the voltage across the resistor at t = 0- is non zero
D. the resistor current eventually falls to zero
Answer» C. the voltage across the resistor at t = 0- is non zero
Discussion
32.

A constant voltage of 60 V is applied at t = 0 across a series R-L circuit as shown in the figure. Determine the current (in A) in the circuit at t = 0 +

A. 4
B. 3
C. 0
D. 2
Answer» D. 2
Discussion
33.

A 100 Ω resistor and a 10 μF capacitor are connected to a 300 V battery. At time t = 0, the battery is switched out of the circuit, leaving only the capacitor and resistor. 4 msec after the switch is closed, the current in the resistor will be

A. 6 mA
B. 18 mA
C. 406 mA
D. 55 mA
Answer» E.
Discussion
34.

During discharging of a capacitor of C = 100 μf through a resistance of 1 KΩ applied with 50 V, the voltage at the time of its time constant is:

A. 18.5 V
B. 20 V
C. 15 V
D. 50 V
Answer» B. 20 V
Discussion
35.

After _________ number of time constants, the transient portion reaches more than 99% of its final value.

A. 3
B. 5
C. 1
D. 0
Answer» C. 1
Discussion
36.

Consider the following statements:1. Voltage across a capacitor cannot change abruptly.2. Voltage across an inductor cannot change abruptly.3. Current through a capacitor cannot change abruptly.4. Current through an inductor cannot change abruptly.Which of these statements are correct?

A. 1 and 2 only
B. 2 and 3 only
C. 3 and 4 only
D. 1 and 4 only
Answer» E.
Discussion
37.

A coil has R = 10 Ω and L = 15 H. The Voltage at the Instant when the current is 10 A and Increasing at the rate of 5 A/s will be

A. 125 V
B. 150 V
C. 175 V
D. 200 V
Answer» D. 200 V
Discussion
38.

In any network the current will be seen to be consisting of a forced current and a natural current. A forced current is

A. A steady-state current with external source but a natural current is a transient current in a closed circuit with no external source.
B. A transient current with external source but a natural current is a steady-state current in a closed circuit with no external source.
C. A steady-state current in a closed circuit without external source, while a natural current is a transient current with an external source.
D. A transient current in a closed circuit without external source, while a natural current is a steady-state current with an external source.
Answer» B. A transient current with external source but a natural current is a steady-state current in a closed circuit with no external source.
Discussion
39.

A coil having resistance of 10 Ω and inductance of 1 H is switched on to a direct voltage of 100 V. The steady-state value of the current will be

A. 10 A
B. 15 A
C. 20 A
D. 25 A
Answer» B. 15 A
Discussion
40.

An ideal current source is connected to the disconnected circuit shown in the figure at t = 0. The time constant of the circuit is

A. RC/2
B. RC
C. 2 RC
D. 9 RC/2
Answer» D. 9 RC/2
Discussion
41.

In the circuit shown below, the switch S1 is closed at t = 0 seconds. Switch S2 is opened at t = 0 seconds.The current flowing through the inductor of 0.3 H at t = 8 mili seconds is:

A. 0.65 A
B. 0.32 A
C. 0.26 A
D. 0.18 A
Answer» B. 0.32 A
Discussion
42.

A 20 Ω resistor and 1000 microfarad capacitor are connected in series to a DC supply of 5V through a switch. What is the current through the circuit at the instant of closing the switch?

A. 1A
B. 0A
C. 0.5A
D. 0.25A
Answer» E.
Discussion
43.

In the circuit shown in figure below, it is desired to have a constant direct current i(t) through the ideal inductor L. The nature of the voltage source v(t) must be:

A. constant voltage
B. linearly increasing voltage
C. an ideal impulse
D. exponentially increasing voltage
Answer» D. exponentially increasing voltage
Discussion