Electronics and Communication Engineering - Analog Electronics

11. 

In figure The minimum and maximum load currents are

A. 0 and 60 mA
B. 0 and 120 mA
C. 10 mA and 60 mA
D. 10 mA and 120 mA

Answer: Option B

Explanation:

When RL = ∞, IL = 0,

When RL = 100 Ω, or 120 mA.


12. 

In figure, VEB = 0.6 V, β = 99. Then VC and IC are

A. 9.3 V and 1.98 mA respectively
B. 4.6 V and 1.98 mA respectively
C. 9.3 V and 0.02 mA respectively
D. 4.6 V and 0.02 mA respectively

Answer: Option A

Explanation:

VC = 20 - 1.98 x 10-3 x 5.4 x 103 9.3 V.


13. 

The input impedance of op-amp circuit of figure is

A. 120 k ohm
B. 110 k ohm
C. infinity
D. 10 k ohm

Answer: Option D

Explanation:

Due to the presence of virtual ground at input, the resistance in the series path of input of inverting amplifier is input impedance.


14. 

In a BJT circuit a pnp transistor is replaced by npn transistor. To analyse the new circuit

A. all calculations done earlier have to be repeated
B. replace all calculated voltages by reverse values
C. replace all calculated currents by reverse values
D. replace all calculated voltages and currents by reverse values

Answer: Option D

Explanation:

All voltages and currents have reverse polarity.


15. 

To protect the diodes in a rectifier and capacitor input filter circuit it is necessary to use

A. surge resistor
B. surge inductor
C. surge capacitor
D. both (a) and (b)

Answer: Option A

Explanation:

Resistor reduces surge current.