# Electronic Devices and Circuits Questions and Answers – Transistor Amplifier Response, Taking Source Resistance into Account

This set of Electronic Devices and Circuits Multiple Choice Questions & Answers (MCQs) focuses on “Transistor Amplifier Response, Taking Source Resistance into Account”.

1. What does the static characteristic curve of a transistor define?
b) Current
c) Voltage
d) It is not applicable for transistors

Explanation: The static transistor curve of a transistor defines the steady state relations between the input and output current and voltages. They are calculated and plotted with the help of DC measurements and linear analysis is performed.

2. How many known variables do we need to perform a linear analysis of a transistor circuit taking source resistance into account?
a) 3
b) 5
c) 6
d) 4

Explanation: There are a total of 6 variables in a transistor circuit taking source resistance into account. A transistor is a three-terminal device with each terminal having current and voltage measurements. We require any four variables to determine the other two variables of a transistor circuit taking source resistance into account.

3. Which of the following is an independent variable in a linear analysis of a common base transistor?
a) Base current
b) Collector base voltage
c) Collector current
d) Collector emitter voltage

Explanation: In a linear analysis of a common base transistor, we have two independent variables. The collector base voltage is an independent variable and the collector current is the dependent variable. We can obtain IC using VCB from the characteristic curve.

4. What frequency should be used to check the linear analysis of a transistor?
a) High frequency
b) Medium-high frequency
c) Medium-low frequency
d) Low frequency

Explanation: Low frequency conditions are used to check the linear analysis of transistor models. This is because, under low frequency d-c conditions the value of emitter current is almost equal to the value of collector current.

5. Which of the following is an independent variable in a linear analysis of a common base transistor?
a) Collector emitter voltage
b) Collector current
c) Emitter base voltage
d) Emitter current

Explanation: In a linear analysis of a common base transistor, we have two independent variables. The emitter current is an independent variable and the emitter base voltage is the dependent variable. We can obtain VEB using IE from the characteristic curve.

6. Where is the operating point of transistor located in a linear analysis?
a) Linear region
b) Saturation region
c) Cut-off region
d) It is not located on this graph

Explanation: The operating point of the quiescent operating point is in the linear region of the output of the characteristic curve. In this region the input variations are proportional to the output variations and are easy to determine.

7. Which of the following is an inference made from the linear analysis of a transistor circuit taking source resistance into account?
a) 99% of the collector current flows to the emitter
b) 99% of the emitter current flows to the collector
c) 0.99% of the collector current flows to the emitter
d) 0.99% of the emitter current flows to the collector

Explanation: While performing the linear analysis of a transistor circuit taking source resistance into account we observe that 99% of the collector current flows to the emitter. Current always flows from the collector to the emitter and not the other way around since the emitter terminal is usually grounded.

8. What is the function of a capacitor in the linear analysis of a transistor?
a) To find the operating point
b) To block d-c signals
c) To block a-c signals
d) Makes no difference

Explanation: Capacitors are used in the linear analysis of a transistor circuit taking source resistance into account to block out and isolate the d-c signals while letting the a-c signals pass through. This is useful to calculate the load line in the analysis of the transistor.

9. What is the equation of the load line in the linear analysis of a transistor?
a) VCE = VCC + IB RL
b) VCE = VCC – IB RL
c) VCE = VCC + IC RL
d) VCE = VCC – IC RL

Explanation: Let the collector voltage supply be VCC in series with a load resistor RL. A straight line superimposed on the collector characteristic will provide us with the load line. The equation for the load line is VCE = VCC – IC RL.

10. What do the small signal parameters in a transistor circuit taking source resistance into account vary with respect to in the linear analysis?
b) Bias point
c) Temperature
d) Makes no difference

Explanation: The small signal parameters in a transistor circuit taking source resistance into account vary with respect to the bias point in the linear analysis model. This occurs even in the linear region of the characteristic curve of the transistor.

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

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