9294 + Mcqs in Electronics and Communication Engineering Page 64 McqOptions

3151.	The Laplace transforms of voltage function shown in figure is
A.	<img src="/_files/images/electronics-and-communication-engineering/networks-analysis-and-synthesis/110-503-2.png">
B.	<img src="/_files/images/electronics-and-communication-engineering/networks-analysis-and-synthesis/110-503-3.png">
C.	<img src="/_files/images/electronics-and-communication-engineering/networks-analysis-and-synthesis/110-503-4.png">
D.	<img src="/_files/images/electronics-and-communication-engineering/networks-analysis-and-synthesis/110-503-5.png">
Answer» D. <img src="/_files/images/electronics-and-communication-engineering/networks-analysis-and-synthesis/110-503-5.png">

Discussion

3152.	Discharge breakdown in insulators is due to voids.
A.	True
B.	False
Answer» B. False

Discussion

3153.	A dc machine has 6 poles all connected in series. Each pole has 9 H inductance and field current is 2 A. Total inductance and total energy stored are
A.	9 H and 18 J
B.	18 H and 36 J
C.	54 H and 108 J
D.	108 H and 216 J
Answer» D. 108 H and 216 J

Discussion

3154.	In figure, the switch has been closed position for a long time. At t = 0 the switch is opened. At t = 0+, the current ic is
A.	I
B.	0
C.	infinite
D.	<img src="/_files/images/electronics-and-communication-engineering/networks-analysis-and-synthesis/102-343-2.png">
Answer» B. 0

Discussion

3155.	A circuit has two branches 1 and 2 in parallel. If \|Q1\| = 8 KVAR and \|Q2\| = 6 KVAR, the magnitude of total kvar drawn form supply will be
A.	14 KVAR
B.	2 KVAR
C.	zero
D.	14 or 2 KVAR
Answer» E.

Discussion

3156.	The driving point impedance Z1 is given by
A.	<img src="/_files/images/electronics-and-communication-engineering/networks-analysis-and-synthesis/130-808-2.png">
B.	<img src="/_files/images/electronics-and-communication-engineering/networks-analysis-and-synthesis/130-808-3.png">
C.	<img src="/_files/images/electronics-and-communication-engineering/networks-analysis-and-synthesis/130-808-4.png">
D.	<img src="/_files/images/electronics-and-communication-engineering/networks-analysis-and-synthesis/130-808-5.png">
Answer» E.

Discussion

3157.	A specimen of a material has a resistivity of 1.78 x 108 ohm-m. The material is
A.	semiconductor
B.	conductor
C.	semiconductor or conductor
D.	insulator
Answer» E.

Discussion

3158.	Power is drawn from a source at power factor 0.7. Pav = 300 watt. The reactive power is
A.	0
B.	105
C.	100 VA
D.	107 VA
Answer» E.

Discussion

3159.	Two capacitors each of capacitance C and breakdown voltage V are joined in series. The capacitance and breakdown voltage of the combination is
A.	0.5 C and 2 V
B.	0.5 C and 0.5 V
C.	C and V
D.	2 C and 2 V
Answer» B. 0.5 C and 0.5 V

Discussion

3160.	The current wave shown in figure is applied at t = 0 to a 0.1 F capacitor. At t = 1 s, the voltage across capacitor is
A.	0 V
B.	10 V
C.	20 V
D.	40 V
Answer» D. 40 V

Discussion

3161.	A capacitor can be represented by a capacitance C in parallel with a resistance R. For a good capacitor, the resistance R should be
A.	very high
B.	high
C.	very low
D.	low
Answer» B. high

Discussion

3162.	If a sheet of a mica is inserted between the plates of an air capacitor, the capacitance
A.	will increase
B.	will return the same
C.	will decrease
D.	may increase or decrease
Answer» B. will return the same

Discussion

3163.	The natural frequency Sn of the given circuit is
A.	- 1
B.	+ 1
C.	1/2
D.	- 2
Answer» B. + 1

Discussion

3164.	For addition and subtraction operations, phasors
A.	must be represented in polar form
B.	must be represented in rectangular form
C.	may be represented in any form
D.	none of the above
Answer» C. may be represented in any form

Discussion

3165.	Two coils are connected in parallel. Their fluxes are adding. If the connections of one of the coils are reversed, the total inductance of the arrangement
A.	will decrease
B.	may increase or decrease
C.	will remain the same
D.	will increase
Answer» B. may increase or decrease

Discussion

3166.	The equivalent unit of joule is
A.	newton
B.	newton-meter
C.	newton-metre
D.	<sup>2</sup>
E.	none of the above
Answer» C. newton-metre

Discussion

3167.	The graph of a network has 6 branches with 3 tree branches. The minimum number of equations required for solution of network is
A.	2
B.	3
C.	4
D.	5
Answer» C. 4

Discussion

3168.	In figure, S is closed at t = 0. At t = t1, I = 1 A and di/dt = 1 A/s. Then the value of L is
A.	1 H
B.	2 H
C.	3 H
D.	4 H
Answer» C. 3 H

Discussion

3169.	In the circuit of figure, the switch is closed at t = 0. At t = 0+ the current supplied by battery is
A.	0 A
B.	5 A
C.	less than 5A
D.	infinity
Answer» B. 5 A

Discussion

3170.	A two branch parallel tuned circuit has 100 &ohm; resistance and 0.1 H inductance in one branch and 10-6 F capacitor in the other. At resonance frequency, the dynamic resistance is
A.	10 &ohm;
B.	100 &ohm;
C.	1000 &ohm;
D.	10000 &ohm;
Answer» D. 10000 &ohm;

Discussion

3171.	In figure, the current through R, after the steady state condition is reached, is
A.	I
B.	0
C.	<img src="/_files/images/electronics-and-communication-engineering/networks-analysis-and-synthesis/101-339-1.png">
D.	infinite
Answer» B. 0

Discussion

3172.	The number of electrons in motion at the instant of positive peak of a symmetrical ac wave is the same as that at the instant of negative peak.
A.	True
B.	False
Answer» B. False

Discussion

3173.	Special circuits using neon tubes, contact relays and capacitors are used in many domestic appliances. The role of capacitor in figure is to
A.	reduce power loss
B.	function as resistor when relay is on
C.	delay the operation of the contact relay after switching on
D.	open circuit the relay terminals
Answer» D. open circuit the relay terminals

Discussion

3174.	A series R, L, C circuit has R = 2&ohm;, L = 1H, C = 1 F. It is connected to an ac variable frequency source of peak voltage 10 V. At resonance the power supplied by the source will be
A.	50 &ohm;
B.	25 &ohm;
C.	12.5 &ohm;
D.	6.25 &ohm;
Answer» C. 12.5 &ohm;

Discussion

3175.	Three identical coils each having self inductance L are connected in series so that the fluxes of all the three are in the same direction. If mutual inductance between each pair of coils is M, the total inductance of the arrangement is
A.	3 L + 9 M
B.	1.5 L + 3 M
C.	3 L + 3 M
D.	3 L + 6 M
Answer» C. 3 L + 3 M

Discussion

3176.	In a resistive ac circuit, the current __________ the voltage by __________ .
A.	lags, 90
B.	lags, 45
C.	lags, 0
D.	leads 90
Answer» D. leads 90

Discussion

3177.	KVL for second loop in figure is
A.	<img src="/_files/images/electronics-and-communication-engineering/networks-analysis-and-synthesis/107-451-1.png">
B.	<img src="/_files/images/electronics-and-communication-engineering/networks-analysis-and-synthesis/107-451-2.png">
C.	<img src="/_files/images/electronics-and-communication-engineering/networks-analysis-and-synthesis/107-451-3.png">
D.	<img src="/_files/images/electronics-and-communication-engineering/networks-analysis-and-synthesis/107-451-4.png">
Answer» C. <img src="/_files/images/electronics-and-communication-engineering/networks-analysis-and-synthesis/107-451-3.png">

Discussion

3178.	When two coupled coils of equal self inductance are cormected 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 maximum value of inductance when they are connected in parallel is
A.	2 mH
B.	3 mH
C.	4 mH
D.	6 mH
Answer» C. 4 mH

Discussion

3179.	An R-L series circuit is excited by a voltage v(t). The circuit was initially relaxed. Which of the following sources of v(t) would cause maximum current at t = 0+?
A.	unit step
B.	unit impulse
C.	unit ramp
D.	unit step plus unit ramp
Answer» C. unit ramp

Discussion

3180.	In a linear circuit, the superposition principle can be applied to calculate the
A.	voltage and power
B.	voltage and current
C.	current and power
D.	voltage, current and power
Answer» C. current and power

Discussion

3181.	If A = 7 15, A2 is
A.	49 225
B.	49 30
C.	49 15
D.	49 7.5
Answer» C. 49 15

Discussion

3182.	The colour coding of a resistors shows 100 K, 10%. When the resistance was measured with an ohmmeter, it read
A.	95 K
B.	80 K
C.	120 K
D.	85 K
Answer» B. 80 K

Discussion

3183.	The circuit in figure has reached steady values with switch open. If switch is closed at t = 0 the voltage across 2 F capacitance at t = 0+ is
A.	zero
B.	4 V
C.	6 V
D.	10 V
Answer» B. 4 V

Discussion

3184.	The output voltage of a charger is
A.	less than battery voltage
B.	same as battery voltage
C.	more than battery voltage
D.	same or more than battery voltage
Answer» D. same or more than battery voltage

Discussion

3185.	A planar graph has 6 nodes and 7 branches. The number of meshes in the dual graph is
A.	2
B.	3
C.	4
D.	6
Answer» B. 3

Discussion

3186.	An ac voltage 20 sin 1000t feeds an R-C series circuit. R = 8 &ohm; and active power is 4 W. The power factor is
A.	1
B.	0.8
C.	0.6
D.	0.4
Answer» E.

Discussion

3187.	For a sine wave the average value is calculated over half the cycle.
A.	True
B.	False
Answer» B. False

Discussion

3188.	Two resistances of 2 &ohm; each are connected in series. A shunt having zero resistance is connected across the combination. The overall resistance will be
A.	4 &ohm;
B.	1 &ohm;
C.	0.5 &ohm;
D.	zero
Answer» E.

Discussion

3189.	An RLC series circuit has R = 30 &ohm;, XL = 30 &ohm; and XC = 30 W. Its impedance is
A.	30 0 .
B.	30 45
C.	42.42 45
D.	90 45 .
Answer» B. 30 45

Discussion

3190.	R, L and C are in parallel. The circuit is switched on to a constant current source I at t = 0. At t = the current through inductance is I.
A.	True
B.	False
Answer» B. False

Discussion

3191.	A 2 mH inductor with some initial current can be represented as shown below, where s is the Laplace transform variable. The value of initial current is
A.	0.5 A
B.	1.0 A
C.	2.0 A
D.	0.0 A
Answer» B. 1.0 A

Discussion

3192.	As temperature increases, the temperature coefficient of metals increases.
A.	True
B.	False
Answer» C.

Discussion

3193.	In a 3 phase system, the zero sequence component of line to line voltages is zero
A.	if line to line voltages are balanced
B.	if line to line voltages are unbalanced
C.	if line to line voltages are balanced or unbalanced
D.	if degree of unbalanced in line to line voltages is small
Answer» D. if degree of unbalanced in line to line voltages is small

Discussion

3194.	Magnetic effect of current is used in generators but not in motors.
A.	True
B.	False
Answer» C.

Discussion

3195.	In figure, A is ideal ammeter having zero resistance. It will read __________ ampere.
A.	2
B.	2.5
C.	3
D.	4
Answer» D. 4

Discussion

3196.	Threshold of perception occurs at a current of about 1 mA.
A.	True
B.	False
Answer» B. False

Discussion

3197.	The average value of delayed full wave rectified sine wave (figure) is
A.	<img src="/_files/images/electronics-and-communication-engineering/networks-analysis-and-synthesis/123-707-2.png">
B.	<img src="/_files/images/electronics-and-communication-engineering/networks-analysis-and-synthesis/123-707-3.png">
C.	<img src="/_files/images/electronics-and-communication-engineering/networks-analysis-and-synthesis/123-707-4.png">
D.	<img src="/_files/images/electronics-and-communication-engineering/networks-analysis-and-synthesis/123-707-5.png">
Answer» D. <img src="/_files/images/electronics-and-communication-engineering/networks-analysis-and-synthesis/123-707-5.png">

Discussion

3198.	The current wave shown in figure is applied by a 0.1 F capacitor at t = 0. At t = 0+, the voltage across capacitor is
A.	0
B.	4 V
C.	10 V
D.	20 V
Answer» B. 4 V

Discussion

3199.	Assertion (A): In a circuit having high inductance, reactive power may be more than apparent power.Reason (R): Reactive power = VI sin .
A.	Both A and R are true and R is correct explanation of A
B.	Both A and R are true and R is not the correct explanation of A
C.	A is true but R is false
D.	A is false but R is true
Answer» E.

Discussion

3200.	A two branch parallel circuit has a 10 &ohm; resistance and 0.5 H inductance in one branch and a 100 F capacitor in the second branch. It is fed from 100 V ac supply. At resonance, the source current is
A.	10 A
B.	1 A
C.	0.2 A
D.	0.05 A
Answer» D. 0.05 A

Discussion

Explore topic-wise MCQs in Engineering.

The Laplace transforms of voltage function shown in figure is

Discharge breakdown in insulators is due to voids.

A dc machine has 6 poles all connected in series. Each pole has 9 H inductance and field current is 2 A. Total inductance and total energy stored are

In figure, the switch has been closed position for a long time. At t = 0 the switch is opened. At t = 0+, the current ic is

A circuit has two branches 1 and 2 in parallel. If |Q1| = 8 KVAR and |Q2| = 6 KVAR, the magnitude of total kvar drawn form supply will be

The driving point impedance Z1 is given by

A specimen of a material has a resistivity of 1.78 x 108 ohm-m. The material is

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The current wave shown in figure is applied at t = 0 to a 0.1 F capacitor. At t = 1 s, the voltage across capacitor is

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The natural frequency Sn of the given circuit is

For addition and subtraction operations, phasors

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Special circuits using neon tubes, contact relays and capacitors are used in many domestic appliances. The role of capacitor in figure is to

A series R, L, C circuit has R = 2&amp;ohm;, L = 1H, C = 1 F. It is connected to an ac variable frequency source of peak voltage 10 V. At resonance the power supplied by the source will be

Three identical coils each having self inductance L are connected in series so that the fluxes of all the three are in the same direction. If mutual inductance between each pair of coils is M, the total inductance of the arrangement is

In a resistive ac circuit, the current __________ the voltage by __________ .

KVL for second loop in figure is

When two coupled coils of equal self inductance are cormected 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 maximum value of inductance when they are connected in parallel is

An R-L series circuit is excited by a voltage v(t). The circuit was initially relaxed. Which of the following sources of v(t) would cause maximum current at t = 0+?

In a linear circuit, the superposition principle can be applied to calculate the

If A = 7 15, A2 is

The colour coding of a resistors shows 100 K, 10%. When the resistance was measured with an ohmmeter, it read

The circuit in figure has reached steady values with switch open. If switch is closed at t = 0 the voltage across 2 F capacitance at t = 0+ is

The output voltage of a charger is

A planar graph has 6 nodes and 7 branches. The number of meshes in the dual graph is

An ac voltage 20 sin 1000t feeds an R-C series circuit. R = 8 &amp;ohm; and active power is 4 W. The power factor is

For a sine wave the average value is calculated over half the cycle.

Two resistances of 2 &amp;ohm; each are connected in series. A shunt having zero resistance is connected across the combination. The overall resistance will be

An RLC series circuit has R = 30 &amp;ohm;, XL = 30 &amp;ohm; and XC = 30 W. Its impedance is

R, L and C are in parallel. The circuit is switched on to a constant current source I at t = 0. At t = the current through inductance is I.

A 2 mH inductor with some initial current can be represented as shown below, where s is the Laplace transform variable. The value of initial current is

As temperature increases, the temperature coefficient of metals increases.

In a 3 phase system, the zero sequence component of line to line voltages is zero

Magnetic effect of current is used in generators but not in motors.

In figure, A is ideal ammeter having zero resistance. It will read __________ ampere.

Threshold of perception occurs at a current of about 1 mA.

The average value of delayed full wave rectified sine wave (figure) is

The current wave shown in figure is applied by a 0.1 F capacitor at t = 0. At t = 0+, the voltage across capacitor is

Assertion (A): In a circuit having high inductance, reactive power may be more than apparent power.Reason (R): Reactive power = VI sin .

A two branch parallel circuit has a 10 &amp;ohm; resistance and 0.5 H inductance in one branch and a 100 F capacitor in the second branch. It is fed from 100 V ac supply. At resonance, the source current is

A two branch parallel tuned circuit has 100 &ohm; resistance and 0.1 H inductance in one branch and 10-6 F capacitor in the other. At resonance frequency, the dynamic resistance is

A series R, L, C circuit has R = 2&ohm;, L = 1H, C = 1 F. It is connected to an ac variable frequency source of peak voltage 10 V. At resonance the power supplied by the source will be

In a resistive ac circuit, the current the voltage by .

An ac voltage 20 sin 1000t feeds an R-C series circuit. R = 8 &ohm; and active power is 4 W. The power factor is

Two resistances of 2 &ohm; each are connected in series. A shunt having zero resistance is connected across the combination. The overall resistance will be

An RLC series circuit has R = 30 &ohm;, XL = 30 &ohm; and XC = 30 W. Its impedance is

A two branch parallel circuit has a 10 &ohm; resistance and 0.5 H inductance in one branch and a 100 F capacitor in the second branch. It is fed from 100 V ac supply. At resonance, the source current is