Circuit Theory

Q.

The circuit diagram shown here corresponds to the logic gate

1. AND Gate

2. OR Gate

3. NOR Gate

4. NAND Gate

Q.

An alternating current is given by the equation $i=i_1\sin \omega t+i_2\cos \omega t$. The rms current will be:

1. $\frac{1}{2}{({i_1}^2+{i_2}^2)}^{1/2}$

2. $\frac{1}{\sqrt{2}}{({i_1}^2+{i_2}^2)}^{1/2}$

3. $\frac{1}{\sqrt{2}}{(i_1+i_2)}^2$

4. $\frac{1}{\sqrt{2}}(i_1+i_2)$

Q. The equivalent resistance between the terminals A and B is $\Omega$

1. 3

Q. The current through the 2 k$\Omega$ resistance in the circuit shown is

1. 0 mA
2. 1 mA
3. 2 mA
4. 6 mA

Q. A balanced three-phase, star-connected load of 100 kW takes a leading current of 80 A, when connected across a 3-phase 1100 V, 50 Hz supply. The capacitance of the load per phase is

1. $531.4\mu F$
2. $5.99\mu F$
3. $7.49\mu F$
4. $5.21\mu F$

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

1. the bulb together consume 100W
2. the bulb together consume 50 W
3. the 60 W bulb glows brighter
4. the 40 W bulb glows brighter

Q. In the circuit shown in the figure, the value of the current i will be given by

1. 0.31 A
2. 1.25 A
3. 1.75 A
4. 2.5 A

Q.

A transformer of efficiency $90\%$ draws an input power of $4kW$. An electrical appliance connected across the secondary draws a current of $6A$. The impedance of the device is

1. $60\Omega$

2. $50\Omega$

3. $80\Omega$

4. $100\Omega$

5. $120\Omega$

Q. The rms value of the current in a wire which carries a d.c current of 10A and a sinusoidal alternating current of peak value 20 A is

1. 10 A
2. 14.14 A
3. 15 A
4. 17.32 A

Q. The z-parameters of the two port network shown in the figure are $Z_{11}=40\Omega ,Z_{12}=60\Omega ,Z_{21}=80\Omega$ and $Z_{22}=100\Omega$. The average power delivered to $R_L=20\Omega$, in watts, is

1. 35.55

Q. The rms value of the current i(t) in the circuit shown below is

1. $\frac{1}{2}A$
2. $\frac{1}{\sqrt{2}}A$
3. 1 A
4. $\sqrt{2}A$

Q. The rms value of a half wave rectified symmetrical square wave current of 2 A is

1. $\sqrt{2}$ A
2. 1 A
3. $\frac{1}{\sqrt{2}}$ A
4. $\sqrt{3}$ A

Q. Twelve $1\Omega$ resistances are used as edges to form a cube. The resistance between two diagonally opposite corners of the cube is

1. $\frac{5}{6}\Omega$
2. $1\Omega$
3. $\frac{6}{5}\Omega$
4. $\frac{3}{2}\Omega$

Q. A practical current source is usually represented by

1. a resistance in series with an ideal current source
2. a resistance in parallel with an ideal current source.
3. a resistance in parallel with an ideal voltage source.
4. none of these

Q.

For the combination of resistors shown in the following figure, find the equivalent resistance between $M$ and $N$

Q. Given two coupled inductors $L_1$ and $L_2$, their mutual inductance $M$ satisfies

1. $M=\sqrt{L_1^2+L_2^2}$
2. $M>\frac{(L_1+L_2)}{2}$
3. $M>\sqrt{L_1{L}_2}$
4. $M\le \sqrt{L_1{L}_2}$

Q. Two 2 H inductance coils are connected in series and are also magnetically coupled to each other. The coefficient of coupling being 0.1. The total inductance of the combination can be

1. 0.4 H
2. 3.2 H
3. 4.0 H
4. 4.4 H

Q.

What are RC and RL circuits used for?

Q. The power dissipated by the 10 $\Omega$ resistor in the circuit shown below is ______ W.

1. 3.32

Q. Two impedances $Z_1=(20+j10)\Omega$ and $Z_2=(10-j30)\Omega$ are connected in parallel and this combination is connected in series with $Z_3=30+jX.$ The value of $X$ which will produce resonance is

1. 3.86 $\Omega$
2. 50 $\Omega$
3. 13 $\Omega$
4. 0.26 $\Omega$

Q. The RMS value of the voltage u(t) = 3 + 4cos(3t) is

1. $\sqrt{17}$ V
2. 5 V
3. 7 V
4. $(3+2\sqrt{2})$ V

Q. Three capacitors $C_1,C_2$ and $C_3$ whose values are $10\mu F,5\mu F$ and 2$\mu F$ respectively, have breakdown voltages of 10 V, 5 V and 2 V respectively. For the interconnection shown below, the maximum safe voltage in volts that can be applied across the combination, and the corresponding total charge in $\mu C$ stored in the effective capacitance across the terminals are, respectively

1. 2.8 and 36
2. 7 and 119
3. 2.8 and 32
4. 7 and 80

Q.

Plot the input characteristics of BJT mentioning different regions.

Q. A balanced abc-sequence Y-connected source with $V_{an}=100\angle {10}^{\circ }$ V is connected to a $\Delta$-connected balanced load with impedence $(8+j4)\Omega$ per phase. Then the line current $I_c$ is

1. $33.54\angle {103.43}^{\circ }$
2. $58.1\angle {103.43}^{\circ }$
3. $19.36\angle -{138.4}^{\circ }$
4. $41.3\angle {133.43}^{\circ }$

Q. An electric circuit with 10 branches and 7 nodes will have ________ loop equations

1. 3
2. 4
3. 7
4. 10

Q. The power delivered by the current source, in the figure, is____.

1. 3

Q. The value of the resistance, R, connected across the terminals, A and B, (ref. Fig.), which will absorb the maximum power, is

1. $4.00k\Omega$
2. $4.11k\Omega$
3. $8.00k\Omega$
4. $9.00k\Omega$

Q. $I_1,I_2$ and $I_3$ in the figure below are mesh currents. The current set of mesh equations for these currents, in matrix form, is

1. $\left[\begin{array}{ccc}1& -1& -2\\ -1& 2& -1\\ -2& -1& 3\end{array}\right]\left[\begin{array}{c}{I}_1\\ I_2\\ I_3\end{array}\right]=\left[\begin{array}{c}{V}_1\\ V_2\\ V_3\end{array}\right]$
2. $\left[\begin{array}{ccc}-3& -1& -2\\ -1& 3& -1\\ -2& -1& 3\end{array}\right]\left[\begin{array}{c}{I}_1\\ I_2\\ I_3\end{array}\right]=\left[\begin{array}{c}{V}_1\\ V_2\\ -V_3\end{array}\right]$
3. $\left[\begin{array}{ccc}3& -1& -2\\ -1& 3& -1\\ -2& -1& 3\end{array}\right]\left[\begin{array}{c}{I}_1\\ I_2\\ I_3\end{array}\right]=\left[\begin{array}{c}{V}_1\\ V_2\\ -V_3\end{array}\right]$
4. $\left[\begin{array}{ccc}3& -1& -2\\ -1& 3& -1\\ -2& -1& -3\end{array}\right]\left[\begin{array}{c}{I}_1\\ I_2\\ I_3\end{array}\right]=\left[\begin{array}{c}{V}_1\\ V_2\\ V_3\end{array}\right]$

Q. For a 2-port network to be reciprocal,

1. $z_{11}$ = $z_{22}$
2. $y_{21}$ = $y_{12}$
3. $h_{21}$ = $-h_{12}$
4. $AD-BC=0$

Q. The current $i_4$ in the circuit of figure is equal to

1. 12 A
2. -12 A
3. 4 A
4. None of these