# Electronic Devices and Circuits Questions and Answers – The Emitter Follower

This set of Electronic Devices and Circuits Multiple Choice Questions & Answers (MCQs) focuses on “The Emitter Follower”.

1. What type of amplifier is an emitter follower amplifier?
a) Voltage amplifier
b) Wideband amplifier
c) Feedback amplifier
d) Power amplifier

Explanation: The emitter follower amplifier is one of the most noticeable feedback amplifiers. It provides a negative current feedback to the circuit. These type of amplifiers are usually used in the end stage or the last stage of a series of amplifiers.

2. How is the input impedance of an emitter follower amplifier?
a) Irrelevant
b) Moderate
c) Low
d) High

Explanation: The construction of an emitter follower circuit are approximately similar to a normal amplifier. One of the most important differentiating feature of an emitter follower circuit is its high input impedance.

3. How is the output impedance of an emitter follower amplifier?
a) Irrelevant
b) Moderate
c) Low
d) High

Explanation: The construction of an emitter follower circuit are approximately similar to a normal amplifier. One of the most important differentiating feature of an emitter follower circuit is its low output impedance.

4. How is the current gain of an emitter follower amplifier?
a) Irrelevant
b) Moderate
c) Low
d) High

Explanation: The construction of an emitter follower circuit are approximately similar to a normal amplifier. One of the most important differentiating feature of an emitter follower circuit is its high current gain.

5. How is the power gain of an emitter follower amplifier?
a) Irrelevant
b) Moderate
c) Low
d) High

Explanation: The construction of an emitter follower circuit are approximately similar to a normal amplifier. One of the most important differentiating feature of an emitter follower circuit is its high power gain.

6. What is the application of an emitter follower amplifier?
a) Positive feedback
b) Voltage gain
c) Power gain
d) Impedance matching

Explanation: The high input impedance along with low output impedance makes the emitter follower amplifier ideal for impedance matching. Along with that, its key characteristics include a comparatively high current and power gain.

7. What type of negative feedback does the emitter follower amplifier provide?
a) Voltage, current and power
b) Voltage
c) Current
d) Power

Explanation: The emitter follower configuration is prominently known for its feedback amplifier qualities. It is a negative feedback network that provides a negative feedback of current to the circuit. It is generally used in the last stage of an amplifying network.

8. What is the value of β in an emitter follower amplifier if Vf = 12V and VO = 12V?
a) 1
b) 124
c) 1.24
d) 0.124

Explanation: The value of β in an emitter follower amplifier configuration can be calculated using β = Vf / VO. Given, Vf = 12V and VO = 12V:
β = Vf / VO = 12 / 12 = 1

9. What is the voltage gain of an emitter follower amplifier?
a) 1
b) β
c) ∞
d) 0

Explanation: The voltage gain of an emitter follower amplifier configuration is roughly equal to unity. AV is approximately equal to 1. This is due to the relatively high input impedance and low output impedance.

10. What is the other name for an emitter follower amplifier configuration?
a) Common collector
b) Common base
c) Common emitter
d) Amplifier circuit

Explanation: The emitter follower circuit configuration is also known as the common collector configuration as it provides a high input impedance and a low output impedance. The emitter follower circuit acts as a buffer stage, and in result is used in several circuits where there is a need to prevent the loading of a circuit.

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

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