Quiz: Electrical Engineering 6 June 2020

Quiz: Electrical Engineering
Exam: NLC
Topic: Measurement and measuring instrument

Each question carries 1 mark.
Negative marking: 1/4 mark
Time: 10 Minute

Q1. The Q-point in a voltage amplifier is selected in the middle of the active region so that
(a) it may give distortion less output
(b) it may need a small dc voltage
(c) the operating point become very stable
(d) less no of resistor is required

Q2. If the emitter resistance in a common-emitter voltage amplifier is not bypassed, it will
(a) reduce both the voltage gain and the input impedance
(b) reduce the voltage gain and increase the input impedance
(c) increase the voltage gain and reduce the input impedance
(d) increase both the voltage gain and input impedance

Q3. A Transistor is said to be useful to be configured as an amplifier when its β is
(a) less than 0
(b) between 0 and 1
(c) between 1 and 50
(d) >50

Q4. Which one of the following is not considered as a characteristic of CE amplifier?
(a) Large current gain
(b) output voltage phase shift of 90°
(c) output voltage phase shift of 180°
(d) Large power gain

Q5. A buffer amplifier has a gain of
(a) infinity
(b) zero
(c) unity
(d) dependent upon the circuit parameters

Q6. A good current buffer has
(a) low input impedance and low output impedance
(b) low input impedance and high output impedance
(c) high input impedance and low output impedance
(d) high input impedance and high output impedance

Q7. Thermal noise in transistor amplifier is also known as
(a) shot noise
(b) Schottky noise
(c) black noise
(d) Johnson noise

Q8. Presence of emitter bypass capacitor adversely affects the
(a) low frequency response
(b) medium frequency response
(c) high frequency response
(d) complete frequency response

Q9. α-cut-off frequency of a bipolar junction transistor
(a) increase with the increase in base width
(b) increase with the increase in emitter width
(c) increase with the increase in collector width
(d) increase with the decrease in base width

Q10. Two identical RC coupled amplifier each having a upper cut-off frequency f_u are cascaded with negligible loading. What is the upper cut-off frequency of the overall amplifier?
(a) (f_u )/(√(√2-1) )
(b) f_u √(√2-1)
(c) f_u/2
(d) 2f_u

Solutions
S1. Ans. (a)
Sol. it may give distortion less output

S2. Ans. (b)
Sol. reduce the voltage gain and increase the input impedance

S3. Ans. (d)
Sol. A Transistor is said to be useful to be configured as an amplifier when its β is greater than 50.

S4. Ans. (b)
Sol. output voltage phase shift of 90°

S5. Ans. (c)
Sol. Unity

S6. Ans. (b)
Sol. low input impedance and high output impedance

S7. Ans. (d)
Sol. Johnson noise

S8. Ans. (a)
Sol. low frequency response

S9. Ans. (d)
Sol. increase with the decrease in base width

S10. Ans. (b)
Sol. f_u √(√2-1)

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