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Electronics and Communication Engineering - Analog Electronics

Exercise : Analog Electronics - Section 4
26.
In figure base current is 10 μA and βdc = 100. Then VE =
5 V
10 V
15 V
20 V
Answer: Option
Explanation:

IC = 1 mA and VCE = 20 - 5 x 103 x 1 x 10-3 = 15 V.

27.
It has been found that in a rectifier circuit with RC filter one RC section reduces ripple by 15%. Two RC sections are used in cascade the reduction in ripple would be
15%
30%
150%
225%
Answer: Option
Explanation:

One filter reduces ripple to 0.15 of initial value. The second filter reduces ripple to 0.15 x 0.15 of initial value.

28.
An op-amp has
low input and output impedance
low input impedance and high output impedance
low output impedance and high input impedance
high output impedance and high input impedance
Answer: Option
Explanation:

High input impedance ensures minimum loading of source. Low output impedance is required for impedance matching at output.

29.
In the figure, assume the op-amp is to be ideal. The output Vo if the circuit is
10 cos (100t)
Answer: Option
Explanation:

KCL at mode one.

... (1)

Applying KCL at node (3)

... (2)

From (1)

V2 = 100 L sin ωt

Put value of V2 in equation (2) and solve for V0 .

30.
As the ratio Rf/RL increases the efficiency of a rectifier increases.
True
False
Answer: Option
Explanation:

As increases efficiency decreases.

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