# Questions & Answers of Two-port Networks

## Weightage of Two-port Networks

Total 11 Questions have been asked from Two-port Networks topic of Electric Circuits subject in previous GATE papers. Average marks 1.55.

In the two-port network shown, the $\style{font-family:'Times New Roman'}{h_{11}}$ parameter $\style{font-family:'Times New Roman'}{\left(where\;h_{11}=\frac{V_1}{I_1}\;when\;V_2=0\right)}$ in ohms is _____________ (up to 2 decimal places).

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

Given

$\begin{array}{l}V_1=A_1V_2+B_1I_2\\I_1=C_1V_2+D_1I_2\\V_2=A_2V_3+B_2I_3\\I_2=C_2V_3+D_2I_3\end{array}$

$A1,\;B1,\;C1,\;D1,\;A2,\;B2,\;C2$ and $D_2$ are the generalized circuit constants. If the Thevenin equivalent circuit at port 3 consists of a voltage source $V_T$ and an impendence $Z_T$ , connected in series, then

The figure shows the power per-phase representation of a phase-shifting transformer connected between buses 1 and 2, where $\alpha$ is a complex number with non-zero real and imaginary parts.

For the given circuit, Ybus and Zbus are bus admittance matrix and bus impedance matrix, respectively, each of size 2 × 2. Which one of the following statements is true?

For the given 2-port network, the value of transfer impedance z21 in ohms is__________

If an ideal transformer has an inductive load element at port 2 as shown in the figure below, the equivalent inductance at port 1 is

The following figure shows the connection of an ideal transformer with primary to secondary turns ratio of 1:100. The applied primary voltage is 100 V (rms), 50 Hz, AC. The rms value of the current I, in ampere, is __________.

The $z$-parameters of the two port network shown in the figure are . The average power delivered to ${R}_{L}=20\Omega$ , in watts, is _______.

In a linear two-port network, when 10 V is applied to Port 1, a current of 4 A flows through Port 2 when it is short-circuited. When 5 V is applied to Port 1, a current of 1.25 A flows through a 1 $\mathrm{\Omega }$ resistance connected across Port 2. When 3 V is applied to Port 1, then current (in Ampere) through a 2 $\mathrm{\Omega }$ resistance connected across Port 2 is _________.

With 10 V dc connected at port A in the linear nonreciprocal two-port network shown below, the following were observed:

(i) 1Ω connected at port B draws a current of 3 A
(ii) 2.5Ω connected at port B draws a current of 2 A

For the same network, with 6 V dc connected at port A, 1Ω connected at port B draws 7/3 A. If 8 V dc is connected to port A, the open circuit voltage at port B is

With 10 V dc connected at port A in the linear nonreciprocal two-port network shown below, the following were observed:

(i) 1Ω connected at port B draws a current of 3 A
(ii) 2.5Ω connected at port B draws a current of 2 A

With 10 V dc connected at port A, the current drawn by 7Ω connected at port B is