43 + Mcqs in Transient Analysis Page 1 McqOptions

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

Explore topic-wise MCQs in Network Theory.

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 ___________.

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:

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

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.

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

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 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 ________.

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

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:

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

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

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

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

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:

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

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

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 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

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

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

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

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

By which of the following elements transients will not occur?

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

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

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

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:

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?

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

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

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 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

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:

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

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 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

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

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

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

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 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?

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:

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

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