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Electronics and Communication Engineering - Analog Electronics

Exercise : Analog Electronics - Section 4
11.

Assertion (A): An op-amp has high voltage gain, high input impedance and low output impedance

Reason (R): Negative feedback increases output impedance

Both A and R are correct and R is correct explanation for A
Both A and R are correct but R is not correct explanation for A
A is correct R is wrong
A is wrong R is correct
Answer: Option
Explanation:

Negative feedback reduces output impedance.

12.
A transistor has a maximum power dissipation of 350 mW at an ambient temperature of 25°C. If derating factor is 2 mW/°C, the maximum power dissipation for 40°C ambient temperature is
300 mW
330 mW
350 mW
380 mW
Answer: Option
Explanation:

Derating improves reliability but does not affect maximum power dissipation.

13.
The output voltage waveform of a CE amplifier is fed to a dc coupled CRO. The trace on the screen will be
dc output voltage
ac output voltage
sum of dc and ac output voltage
either (a) or (b)
Answer: Option
Explanation:

Due to direct coupling between output and CRO both dc and ac output voltage will appear on screen of CRO.

14.
In an RC phase shift oscillator, the total phase shift of the three RC lead networks is
360°
180°
90°
0°
Answer: Option
Explanation:

Each RC network gives 60° phase shift.

15.
In the circuit of figure β = 100 and quiescent value of base current is 20 μA. The quiescent value of collector
current is
0.2 μA
2 μA
2 mA
20 mA
Answer: Option
Explanation:

IC = βIB = 2 mA.

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