Analog Electronic Circuits Questions and Answers – Diode Approximations and Series Connection

 

This set of Analog Circuits Multiple Choice Questions & Answers (MCQs) focuses on “Diode Approximations and Series Connection”.

1. Which of the following models of a semiconductor diode is the most widely used for the purpose of calculation?

a) Approximate Equivalent Model

b) Ideal Diode Model

c) Piecewise Linear Model

d) Hybrid model

View Answer

Answer: a

Explanation: Approximate Equivalent model not only saves time and efforts but also provides results with a considerable amount of accuracy.

2. Statement-1: Piecewise linear model is generally not used for diode analysis.

Statement-2: The value of Rav is negligible as compared to the load resistance.

Which of the following holds true?

a) Statement-1 is true, Statement-2 is true and Statement-2 is a proper explanation for Statement-1

b) Statement-1 is true, Statement-2 is true and Statement-2 is not a proper explanation for Statement-1

c) Statement-1 is true, Statement-2 is false

d) Statement-1 is false, Statement-2 is true

View Answer

Answer: a

Explanation: Piecewise linear model involves a line with a slope equal to 1/Rav. As Rav is low, 1/ Rav is high and the slope becomes almost equal to infinity and hence, it approaches the equivalent circuit model and hence, the piecewise linear model isn’t generally used.

3. From the given circuit diagram, considering the diode to be a silicon semiconductor diode, what is the magnitude of diode current? ( Use an appropriate model of the diode)

analog-electronic-circuits-questions-answers-diode-approximations-series-connection-q3

a) 43 mA

b) 0 mA

c) 4.3 mA

d) 5 mA

View Answer

Answer: c

Explanation: ID = (V-VD)/R = 4.3 mA.

4. From the given circuit diagram, what is the value of diode current?

analog-electronic-circuits-questions-answers-diode-approximations-series-connection-q4

a) 8 mA

b) 7.3 mA

c) 0 mA

d) 7 mA

View Answer

Answer: c

Explanation: As both the diodes are reverse biased, the current in the circuit is zero.

5. From the given circuit diagram, what is the value of diode current?

analog-electronic-circuits-questions-answers-diode-approximations-series-connection-q5

a) 8 mA

b) 0 mA

c) 7.3 mA

d) 7 mA

View Answer

Answer: b

Explanation: As the silicon diode in the circuit is reverse biased, hence the current in the circuit is zero.

6. From the given circuit diagram, what is the value of diode current? Use an appropriate diode model.

analog-electronic-circuits-questions-answers-diode-approximations-series-connection-q6

a) 8 mA

b) 0 mA

c) 7.3 mA

d) 7 mA

View Answer

Answer: d

Explanation: The diodes have a drop of 0.3V for Ge and 0.7V for Silicon in forward bias. We can use the constant voltage model, and hence in forward bias, the current flowing is

ID = (V-VD1-VD2)/R = 7 mA.

7. From the given circuit diagram, what is the value of diode current?

analog-electronic-circuits-questions-answers-diode-approximations-series-connection-q7

a) 2 mA

b) 0 mA

c) 1.3 mA

d) 1 mA

View Answer

Answer: b

Explanation: The diodes in forward bias, have drops of 0.3V for Ge and 0.7V for Si, and the total drops cancel out the source voltage, and hence the diode current is zero.

8. From the given circuit diagram, what is the value of voltage across the resistor?

analog-electronic-circuits-questions-answers-diode-approximations-series-connection-q8

a) 2 V

b) 1.3 V

c) 1 V

d) 0 V

View Answer

Answer: d

Explanation: The diodes in forward bias, have drops of 0.3V for Ge and 0.7V for Si, and the total drops cancel out the source voltage, and hence the diode current is zero. Hence voltage drop is also zero.

9. From the given circuit diagram, what is the value of diode current?

analog-electronic-circuits-questions-answers-diode-approximations-series-connection-q9

a) 2.425 mA

b) 5.2 mA

c) 2.325 mA

d) 0 mA

View Answer

Answer: c

Explanation: Here, ID=(V-VD)/R = 2.325 mA

10. From the given circuit diagram, what is the value of voltage across R2?

analog-electronic-circuits-questions-answers-diode-approximations-series-connection-q10

a) 9.324 V

b) 5.3 V

c) 0 V

d) 5.8125 V

View Answer

Answer: d

Explanation: Here, current I=10-0.7/4k=2.325 mA

Here, VR2 = I x R2 = 5.8125 V.

11. From the given circuit diagram, what is the voltage across diode?

analog-electronic-circuits-questions-answers-diode-approximations-series-connection-q11

a) 10 V

b) 5 V

c) 0.7 V

d) 0 V

View Answer

Answer: a

Explanation: As the diode is reverse biased, the current in the circuit is zero and hence the voltage across the diode is equal to the source voltage = 10 V.

12. From the given circuit diagram, what is the value of diode current?

analog-electronic-circuits-questions-answers-diode-approximations-series-connection-q11

a) 2.425 mA

b) 5.2 mA

c) 2.325 mA

d) 0 mA

View Answer

Answer: d

Explanation: As the diode is reverse biased, the current in the circuit is zero.