# Electronic Devices and Circuits Questions and Answers – Determination of the H-Parameters

This set of Electronic Devices and Circuits Multiple Choice Questions & Answers (MCQs) focuses on “Determination of the H-Parameters”.

1. How do we determine the hybrid parameters h11 and h21of a two – port network?
a) Short circuiting the input terminal
b) Open circuiting the input terminal
c) Short circuiting the output terminal
d) Open circuiting the output terminal

Explanation: There are four h parameters, they are: h11, h12, h21 and h22. To determine the values of h11 and h21 we need to short circuit the output terminal of a given two – port network. Short circuiting the output terminal makes the output terminal voltage V2 equal to zero.

2. In a hybrid model of a two – port network, parameter h11 is also known as?
a) Input conductance
b) Input resistance
c) Output conductance
d) Output resistance

Explanation: The parameter h11 can be calculated by short circuiting the output port. By doing so, we can calculate h11 = V1 / I1. Since this gives h11 the units of volts / ampere or in other words ohms, it is also known as input resistance.

3. How do we determine the value of the hybrid parameter h21 in a two – port network?
a) h21 = I1 / I2
b) h21 = V1 / V2
c) h21 = I2 / I1
d) h21 = V2 / V1

Explanation: To calculate the value of h21, we short circuit the output terminal so the output voltage V2 equals zero. Hence the equation for hybrid parameters becomes, I2 = h21I1 + 0. Therefore, h21 = I2 / I1.

4. Which hybrid parameter is used to calculate forward current gain in a two – port network?
a) h11
b) h12
c) h21
d) h22

Explanation: The hybrid parameter h21 can be calculated by short circuiting the output port. By doing so, we can calculate h21 = I2 / I1. Since this is a ratio between two current units, h21 is unitless. It is known as the forward current gain of the circuit.

5. In a hybrid model, which parameter is known as the output conductance?
a) h11
b) h12
c) h21
d) h22

Explanation: When the input terminal of a two – port device is open circuited, the input current flowing equals to zero. Hence the value of h22 = I2 / V2. The unit of this parameter is ampere / volt or mho. Hence it is known as output conductance.
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6. Which of the following four hybrid parameters is used to calculate reverse voltage gain?
a) h11
b) h12
c) h21
d) h22

Explanation: The hybrid parameter h12 can be calculated by open circuiting the input port. By doing so, we can calculate h12 = V1 / V2. Since this is a ratio between two voltage units, h12 is unitless. It is known as the reverse voltage gain of the circuit.

7. How do we calculate the value of hybrid parameter h12 if V2 = 20V and V1 = 50V in a two – port device?
a) 0.04
b) 0.25
c) 0.4
d) 2.5

Explanation: To find the hybrid parameter h12 we use the below mentioned formula. Given values are V2 = 20V and V1 = 50V.
h21 = V1 / V2 = 50 / 20 = 2.5.

8. How do we determine the hybrid parameters h12 and h22 in a two – port linear device?
a) Short circuiting the input terminal
b) Open circuiting the input terminal
c) Short circuiting the output terminal
d) Open circuiting the output terminal

Explanation: From the four hybrid parameters, to determine the value of h12 and h22 we need to open circuit the input terminal. This in turn makes the current from the input terminal I1 equal to zero.

Sanfoundry Global Education & Learning Series – Electronic Devices and Circuits.