#### Mcq question 40

Question:

The bus admittance matrix for a power system network is

$$\left[ {\begin{array}{*{20}{c}} { - j39.9}&{j20}&{j20}\\ {j20}&{ - j39.9}&{j20}\\ {j20}&{j20}&{ - j39.9} \end{array}} \right]$$

There is a transmission line, connected between buses 1 and 3, which is represented by the circuit shown in figure.

If this transmission line is removed from service, what is the modified bus admittance matrix?

A.

$$\left[ {\begin{array}{*{20}{c}} { - j19.9}&{j20}&0\\ {j20}&{ - j39.9}&{j20}\\ 0&{j20}&{ - j19.9} \end{array}} \right]$$

B.

$$\left[ {\begin{array}{*{20}{c}} { - j39.95}&{j20}&0\\ {j20}&{ - j39.9}&{j20}\\ 0&{j20}&{ - j39.95} \end{array}} \right]$$

C.

$$\left[ {\begin{array}{*{20}{c}} { - j19.95}&{j20}&0\\ {j20}&{ - j39.9}&{j20}\\ 0&{j20}&{ - j19.95} \end{array}} \right]$$

D.

$$\left[ {\begin{array}{*{20}{c}} { - j19.9}&{j20}&{j20}\\ {j20}&{ - j39.9}&{j20}\\ {j20}&{j20}&{ - j19.95} \end{array}} \right]$$

#### Mcq question 41

Question:

The switch in the figure below was closed for a long time. It is opened at t=0. The current in the inductor of 2H for $$t \ge 0$$, is

A.

$$2.5{e^{ - 4t}}$$

B.

$$5{e^{ - 4t}}$$

C.

$$2.5{e^{ - 0.25t}}$$

D.

$$5{e^{ - 0.25t}}$$

#### Mcq question 38

Question:

The input voltage VDC of the buck-boost converter shown below varies from 32V to 72V. Assume that all components are ideal, inductor current is continuous, and output voltage is ripple free. The range of duty ratio D of the converter for which the magnitude of the steady-state output voltage remains constant at 48V is

A.

$$\frac{2}{5} \le D \le \frac{3}{5}$$

B.

$$\frac{2}{3} \le D \le \frac{3}{4}$$

C.

$$0 \le D \le 1$$

D.

$$\frac{1}{3} \le D \le \frac{2}{3}$$

#### Mcq question 37

Question:

The logical gate implemented using the circuit shown below where, V1 and V2 are inputs (with 0V as digital 0 and 5V as digital 1) and Vout is the output, is

A.

NOT

B.

NOR

C.

NAND

D.

XOR

#### Mcq question 36

Question:

The output expression for the karnaugh map shown below is

A.

$$B\bar D + BCD$$

B.

$$B\bar D + AB$$

C.

$$\bar BD + ABC$$

D.

$$B\bar D + ABC$$

#### Mcq question 35

Question:

The approximate transfer characteristic for the circuit shown below with an ideal operational amplifier and diode will be

A.

(A)

B.

(B)

C.

(C)

D.

(D)

#### Mcq question 34

Question:

The load shown in the figure is supplied by a 400V (line to line), 3-phase source (RYB sequence). The load is balanced and inductive, drawing 3464 VA. When the switch S is in position N, thje three watt-meters W1, W2 and W3 read 577.35 W each. If the switch is moved to position Y, the readings of the watt-meters in watts will be:

A.

W1=1732 and W2=W3=0

B.

W1=0, W2=1732 and W3=0

C.

W1=866 and W2=0, W3=866

D.

W1=W2=0 and W3=1732

#### Mcq question 32

Question:

In the system whose signal flow graph is shown in the figure, $${U_1}(s)$$ and $${U_2}(S)$$ are inputs. The transfer function $$\frac{{Y(s)}}{{{U_1}(s)}}$$ is

A.

$$\frac{{{k_1}}}{{JL{s^2} + JRs + {k_1}{k_2}}}$$

B.

$$\frac{{{k_1}}}{{JL{s^2} - JRs - {k_1}{k_2}}}$$

C.

$$\frac{{{k_1} - {U_2}(R + sL)}}{{JL{s^2} + (JR - {U_2}L)s + {k_1}{k_2} - {U_2}R}}$$

D.

$$\frac{{{k_1} - {U_2}(sL - R)}}{{JL{s^2} - (JR + {U_2}L)s - {k_1}{k_2} + {U_2}R}}$$

#### Mcq question 31

Question:

Let the signal $$x(t) = \sum\limits_{k = - \infty }^{ + \infty } {{{( - 1)}^k}\delta (t - \frac{k}{{2000}}} )$$ be passed through an LTI system with frequency response $$H(\omega )$$, as given in the figure below. The Fourier series representation of the output is given as

A.

$$4000 + 4000\cos (2000\pi t) + 4000\cos (4000\pi t)$$

B.

$$2000 + 2000\cos (2000\pi t) + 2000\cos (4000\pi t)$$

C.

$$4000\cos (2000\pi t)$$

D.

$$2000\cos (2000\pi$$

#### Mcq question 29

Question:

Two passive two-port networks are connected in cascade as shown in figure. A voltage source is connected at port 1.Given

$${V_1} = {A_1}{V_2} + {B_1}{I_2}$$
$${I_1} = {C_1}{V_2} + {D_1}{I_2}$$
$${V_2} = {A_2}{V_3} + {B_2}{I_3}$$
$${I_2} = {C_2}{V_3} + {D_2}{I_3}$$
A1, B1, C1, D1, A2, B2, C2 and D2 are the generalised circuit constants. If the Thevenin equivalent circuit at port3 consists of a voltage source VT and an impedance ZT, connected in series, then

A.

$${V_T} = \frac{{{V_1}}}{{{A_1}{A_2}}}$$, $${Z_T} = \frac{{{A_1}{B_2} + {B_1}{D_2}}}{{{A_1}{A_2} + {B_1}{C_2}}}$$

B.

$${V_T} = \frac{{{V_1}}}{{{A_1}{A_2} + {B_1}{C_2}}}$$, $${Z_T} = \frac{{{A_1}{B_2} + {B_1}{D_2}}}{{{A_1}{A_2}}}$$

C.

$${V_T} = \frac{{{V_1}}}{{{A_1} + {A_2}}}$$, $${Z_T} = \frac{{{A_1}{B_2} + {B_1}{D_2}}}{{{A_1} + {A_2}}}$$

D.

$${V_T} = \frac{{{V_1}}}{{{A_1}{A_2} + {B_1}{C_2}}}$$, $${Z_T} = \frac{{{A_1}{B_2} + {B_1}{D_2}}}{{{A_1}{A_2} + {B_1}{C_2}}}$$