Electrical Engineering - Network Theory
Exam Duration: 45 Mins Total Questions : 30
Find the value \(R_{Th}\)in the figure given below.
- (a)
Infinite
- (b)
Zero
- (c)
3/125\(\Omega\)
- (d)
125/3\(\Omega\)
The resonant frequency of the circuit shown in figure is
- (a)
\(1/2\sqrt { 2 } \pi \quad Hz\)
- (b)
\(1/2\pi \quad Hz\)
- (c)
\(1/4\pi \quad Hz\)
- (d)
\(1/\sqrt { 2 } \pi \quad Hz\)
Given two coupled inductors L1 and L2 their mutual inductance M satisfies
- (a)
\(M=\sqrt { { L }_{ 1 }^{ 2 }+{ L }_{ 2 }^{ 2 } } \)
- (b)
\(M>\frac { ({ L }_{ 1 }+{ L }_{ 2 }) }{ 2 } \)
- (c)
\(M>\sqrt { { L }_{ 1 }{ L }_{ 2 } } \)
- (d)
\(M\le \sqrt { { L }_{ 1 }{ L }_{ 2 } } \)
In the below figure, the current source is I \(\angle \)O A, R =1\(\Omega\), the impedance are Zc =- j\(\Omega\) and ZL =2j\(\Omega\). The Thevenin equivalent looking into the circuit across x-y is
- (a)
\(\sqrt { 2 } \angle 0V,(1+2j)\Omega \)
- (b)
\(\sqrt { 2 } \angle 0V,(1+2j)\Omega \)
- (c)
\(2\angle 45^{ 0 }V,(1+j)\Omega \)
- (d)
\(\sqrt { 2 } \angle 45^{ 0 }V,(1+j)\Omega \)
A 50 μFcapacitor, when connected in series with a coil having 400 resistance, resonates at 1000 Hz.Find the inductance of the coil. Also, obtain the circuit current, if the applied voltage is 100 V. Also, calculate the voltage across the capacitor and the coiI at resonance.
- (a)
105.31V
- (b)
101.31V
- (c)
100.31V
- (d)
99.31V
The time constant of the network shown in figure is
- (a)
2RC
- (b)
3RC
- (c)
\(RC\over 2\)
- (d)
\(2RC\over 3\)
In a series RLC circuit for lower frequency, power factor is ........ and for higher frequency, power factor is
- (a)
leading, lagging
- (b)
lagging, leading
- (c)
independent of frequency
- (d)
same in both cases
In below figure, the initial capacitor voltage is zero.The switch is closed at t =0, the final steady-state voltage across the capacitor is
- (a)
20V
- (b)
10V
- (c)
5V
- (d)
0V
A segment of a circuit is shown in below figure in which VR =5 V, Vc = 4sin 2t. The voltage VL is given by
- (a)
3-8 cos 2t
- (b)
32 sin 2t
- (c)
16 sin 2t
- (d)
16 cos 2t
A two-port network is reciprocal if and only if
- (a)
Z11=Z22
- (b)
BC - AD = -1
- (c)
Y12=-Y21
- (d)
h12=h21
Given that F(s) is the one-sided Laplace transform of ((t), the Laplace transform of \(\int_0^tf(\tau)d\tau\) is
- (a)
sF(s)-f(0)
- (b)
\({1\over s}F(s)\)
- (c)
\(\int_0^sF(\tau)d\tau\)
- (d)
\({1\over s}[F(s)-f(0)]\)
Current through and voltage across a device are given in figure. Energy (approximate) absorbed by the device in the interval 0 ≤ t ≤ 2 is
- (a)
8.5J
- (b)
10J
- (c)
11.4J
- (d)
5J
For the graph shown below, correct set is
- (a)
Node Branch Twigs Link 4 6 4 2 - (b)
Node Branch Twigs Link 4 6 3 3 - (c)
Node Branch Twigs Link 5 6 4 3 - (d)
Node Branch Twigs Link 5 5 4 1
The equivalent inductance measured between the terminals 1 and 2 for the circuit shown in figure, is
- (a)
L1 +L2 +M
- (b)
L1 + L2 - M
- (c)
L1 + L2 + 2M
- (d)
L1 + L2 -2M
In the circuit shown below a charge of 500 C is delivered to the 100V source in 1 min. The value of V1 must be
- (a)
266.8V
- (b)
120V
- (c)
60V
- (d)
30V
Two elements are connected in series as shown in figure . Element 1 supplies 42 W of power Elements 2
- (a)
absorbs 72W
- (b)
absorbs 36W
- (c)
absorbs 63W
- (d)
absorbs 144W
Find the voltage across 64\(\Omega\) resistor
- (a)
-64/63V
- (b)
63/64V
- (c)
64/63V
- (d)
-63/64V
The rms value of the periodic waveform given in figure is
- (a)
\(2\sqrt { 6 } A\)
- (b)
\(2\sqrt { 2 } A\)
- (c)
\(\sqrt { \frac { 4 }{ 3 } } A\)
- (d)
1.5 A
An ideal capacitor is charged to a voltage V0 and connected at t=0 across an ideal inductor L. (The circuit now consists of a capacitor and inductor alone). If we take \(\omega _{ 0 }=\frac { 1 }{ \sqrt { LC } } \\ \) , the voltage across the capacitor at time t>0 is given by
- (a)
V0
- (b)
\(V_{ 0 }cos\left( \omega _{ 0 }t \right) \)
- (c)
\(V_{ 0 }sin\left( \omega _{ 0 }t \right) \)
- (d)
\(V_{ 0 }e^{ -\omega _{ 0 }t }cos\left( \omega _{ 0 }t \right) \)
From the given figure, the value of Ia is
- (a)
14 mA
- (b)
-6.5 mA
- (c)
7 mA
- (d)
-21 mA
Find Thevenin's equivalent impedance of the given circuit in figure looking from x-y terminals.
- (a)
\(Z_{ int }=\frac { r_{ 1 }r_{ 2 } }{ r_{ 1 }-r_{ 2 }\alpha \beta } \Omega \)
- (b)
\(Z_{ int }=\frac { r_{ 1 } }{ r_{ 1 }-r_{ 2 }\alpha \beta } \Omega \)
- (c)
\(Z_{ int }=\frac { r_{ 2 } }{ r_{ 2 }-r_{ 1 }\alpha \beta } \Omega \)
- (d)
None of these
A ramp voltage V(t) =100 V, is applied to an RC differentiating circuit with R = 5k\(\Omega \) and C = 4 \(\mu F\).The maximum output voltage is
- (a)
0.2 V
- (b)
2.0 V
- (c)
10.0 V
- (d)
50.0 V
Find out Ix using nodal analysis.
- (a)
-2.5 A
- (b)
2.5 A
- (c)
5 A
- (d)
-5 A
Viewed from the terminals A and 8 the following circuit shown in figure can be reduced to an equivalent circuit of a single voltage source in series with a single resistor with the following parameters:
- (a)
5 V source in serieswith 10\(\Omega \) resistor
- (b)
1 V source in serieswith 2.4 \(\Omega \) resistor
- (c)
15 V source in serieswith 2.4 \(\Omega \) resistor
- (d)
1 V source in serieswith 10\(\Omega \) resistor
In figure, the value of resistance R in \(\Omega \) is
- (a)
10
- (b)
20
- (c)
30
- (d)
40
An AC source of rms voltage 20 V with internal impedance Zs =(1+ 2j) \(\Omega \) feeds a load of impedance ZL =(7 + 4j) \(\Omega \) in the figure below. The reactive power consumed by the load is
- (a)
8 VAR
- (b)
16 VAR
- (c)
28 VAR
- (d)
32 VAR
The switch in the circuit shown was on position a for a long time and is moved to position b at time t =0. The current I(t) for t >0 is given by
- (a)
0.2e-125tu(t) mA
- (b)
20e-1250tu(t) mA
- (c)
0.2e-1250tu(t) mA
- (d)
20e-1000tu(t) mA
In the circuit shown, what value of RL maximizes the power delivered to RL?
- (a)
2.4 \(\Omega \)
- (b)
\(\frac { 8 }{ 3 } \)\(\Omega \)
- (c)
4\(\Omega \)
- (d)
6\(\Omega \)
The Thevenin equivalent impedance ZTh between the nodes P and Q in the following circuit is:
- (a)
1
- (b)
\(1+s+\frac { 1 }{ s } \)
- (c)
\(2+s+\frac { 1 }{ s } \)
- (d)
\(\frac { s^{ 2 }+s+1 }{ s^{ 2 }+2s+1 } \)
\(R=10\Omega \quad L=100\quad mH\) and \(C=10\mu F\)
Selectivity is
- (a)
10
- (b)
1.2
- (c)
0.15
- (d)
0.1