Two-Port Network MCQ

1. The Z-matrix of a 2-port network is given by

Z=\begin{bmatrix} 0.9 & 0.2\\ 0.2 & 0.6 \end{bmatrix}

The element Y22 of the corresponding Y matrix of the same network is given by

  1. 1.2
  2. 0.4
  3. -0.4
  4. 1.8
Answer
Answer. d

2. A passive two-port network is in a steady state. Compared to its input, the steady-state output can never offer

  1. higher voltage
  2. lower impedance
  3. greater power
  4. better regulation
Answer
Answer. c

3. If a two-port network is reciprocal, then we have, with the usual notation, the following relationship

  1. h12 = h21
  2. h12 = -h21
  3. h11 = h22
  4. h11h22 – h12h21 = 1
Answer
Answer. b

4. A two-port device is defined by the following pair of equations:

i1 = 2v1 + v2 and i2 = v1 + v2

Its impedance parameters \begin{bmatrix} z_{11} & z_{12}\\ z_{21} & z_{22} \end{bmatrix} are given by

  1. \begin{bmatrix} 2 & 1\\ 1 & 1 \end{bmatrix}
  2. \begin{bmatrix} 1 & -1\\ -1 & 2 \end{bmatrix}
  3. \begin{bmatrix} 1 & 1\\ 1 & 2 \end{bmatrix}
  4. \begin{bmatrix} 2 & -1\\ -1 & 1 \end{bmatrix}
Answer
Answer. b

5. 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 Ω resistance connected across port 2. When 3 V is applied to port 1, the current (in Ampere) through a 2 Ω resistance connected across port 2 is

  1. 0.545
  2. 0.490
  3. 0.360
  4. 0.708
Answer
Answer. a

6. Consider the following standard symbols for two-port parameters:

  1. h12 and h21 are dimensionless
  2. h11 and B have dimensions of ohms
  3. BC is dimensionless
  4. C is dimensionless

Which of the above are correct?

  1. i, ii and iii only
  2. i, ii and iv only
  3. iii and iv only
  4. i, ii, iii and iv
Answer
Answer. a

7. A 2-port network is represented by the following equations

V1 = 60I1 + 20I2

V2 = 20I1 + 40I2

The ABCD parameters of the above network would be

  1. \begin{bmatrix} 2 & \frac{1}{20}\\ 3 & 100 \end{bmatrix}
  2. \begin{bmatrix} 100 & 3\\ 2 & \frac{1}{20} \end{bmatrix}
  3. \begin{bmatrix} 100 & 20\\ 6 & 3 \end{bmatrix}
  4. \begin{bmatrix} 3 & 100\\ \frac{1}{20} & 2 \end{bmatrix}
Answer
Answer. d

8. The condition for reciprocity for a two-port transmission network is expressed by

  1. \begin{vmatrix} A & B\\ C & D \end{vmatrix}=0
  2. \begin{vmatrix} A & D\\B & C \end{vmatrix}=1
  3. \begin{vmatrix} A & C\\ B & D \end{vmatrix}=0
  4. \begin{vmatrix} A & B\\ C & D \end{vmatrix}=1
Answer
Answer. d

9. A 2-port network is defined by the relation,

V_1=\frac{3}{4}I_1-\frac{1}{4}I_2\; , V_2=-\frac{1}{2}I_1+\frac{1}{2}I_2\;

Then y12 is

  1. 0.5 mho
  2. -0.5 mho
  3. 1 mho
  4. -1 mho
Answer
Answer. c

10. A two-port network is described by the following equations

V1 = 50I1 + 20I2

V2 = 30I1 + 10I2

Then, which one of the following is not correct?

  1. Z12 = 20 Ω
  2. Y12 = 0.2 mho
  3. h12 = 2
  4. A = 25
Answer
Answer. d

11. A two-port network is defined by the relation:

I1 = 5V1 + 3V2

I2 = 2V1 – 7V2

The value of z12 is

  1. 3 Ω
  2. -3 Ω
  3. 3/41 Ω
  4. 2/31 Ω
Answer
Answer. c

12. A, B, C and D represent the transmission parameters of a two-port network. When is the network reciprocal?

  1. AB – CD = 1
  2. AD – BC = 1
  3. AB – CD = 0
  4. AD – BC = 0
Answer
Answer. b

13. The h parameters h11 and h22 are related to z and y parameters as

  1. h11 = z11 and h22 = 1/z22
  2. h11 = z11 and h22 = y22
  3. h11 = 1/y11 and h22 = 1/z22
  4. h11 = 1/y11 and h22 = y22
Answer
Answer. c

14. For a two-port symmetrical bilateral network, if transmission A = 2 and B = 1 ohm, then the value of parameter C is equal to

  1. 3 ohms
  2. 6 ohms
  3. 9 ohms
  4. 12 ohms
Answer
Answer. a

15. The two-port parameter h21 is called

  1. open-circuit output admittance
  2. short-circuit input impedance
  3. open-circuit reverse voltage gain
  4. short-circuit forward current gain
Answer
Answer. d

16. In a two-port network how hybrid parameter is expressed

  1. V1, I2
  2. Y1, I1
  3. I1, I2
  4. V1, V2
Answer
Answer. a

17. When analysing two port network in cascade, which of the following is more convenient to use?

  1. z-parameters
  2. h-parameters
  3. T-parameters
  4. y-parameters
Answer
Answer. c

18. A two port network is reciprocal if

  1. Y11 = Y22
  2. Y12 = Y21
  3. Y12 = -Y21
  4. Y22 = Y21
Answer
Answer. b

19. For a two port reciprocal network, the three transmission parameters are given by A = 3/5, B = 7/5, C = 4/5, what is the value of D?

  1. 1
  2. 3/5
  3. 53/15
  4. 1/2
Answer
Answer. c

20. Which of the following expression shows correct function for ‘Y’ parameter in a two port network?

  1. (V1, V2) = f(I1, I2)
  2. (I1, I2) = f(V1, V2)
  3. (V1, I1) = f(V2, -I2)
  4. (V1, I2) = f(I1, V2)
Answer
Answer. b

21. Two terminals constitute a “Port”, if they satisfy port condition. The port condition indicates

  1. current entering one terminal is equal to the current leaving the other terminal
  2. current entering one terminal and leaving the other terminal is different
  3. no current must enter and leave a port
  4. all the above
Answer
Answer. a

22. A network is said to be reciprocal if

  1. Z12 = Z21
  2. Y12 = Y21
  3. AD – BC = 1
  4. all of these
Answer
Answer. d

23. Two port networks are connected in cascade. The combination is to represent as a single two-port networks. The parameters of the network are obtained by multiplying the individual

  1. z-parameter matrix
  2. h-parameter matrix
  3. y-parameter matrix
  4. ABCD parameter matrix
Answer
Answer. d

24. Which of the following conditions holds good for a 2-port network to be reciprocal?

  1. Z11 = Z22
  2. h12 = h21
  3. Y12 = Y21
  4. BC – AD = -1
Answer
Answer. d

25. In terms of ABCD parameters, a two port network is symmetrical if and only if

  1. A = B
  2. B = C
  3. C = D
  4. D = A
Answer
Answer. d

26. A passive 2-port network is in a steady-state. Compared to its input, the steady state output can never offer

  1. higher voltage
  2. lower impedance
  3. greater power
  4. better regulation
Answer
Answer. c
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