Analog Electronic Circuits Questions and Answers – Parallel and Series Configuration

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

1. From the given circuit, what is the value of current flowing through the 1 k resistor parallel to the diodes?

a) 10 mA
b) 9.3 mA
c) 8.6 mA
d) 0 mA

Explanation: As both the diodes are reverse biased. Voltage drop across the resistor = 10 V. Hence, current = 10 V/1 k = 10 mA.

2. From the given circuit, what is the value of current flowing through the 1 k resistor?

a) 0 mA
b) 10 mA
c) 9.3 mA
d) 0.7 mA

Explanation: As one of the diodes is forward biased, voltage drop across it = 0.7 V. Now, as this diode is in parallel with the given resistor, voltage across resistor = 0.7 V => current = 0.7 mA.

3. In the given circuit, what is the value of current flowing through the forward biased diode?

a) 10 mA
b) 9.3 mA
c) 8.6 mA
d) 0 mA

Explanation: Here, current flowing through R2 = (10-0.7)/1k = 9.3 mA. Also the current through the parallel resistor=0.7 mA. Hence the current through the forward biased diode = (9.3-0.7) = 8.6 mA.

4. In the given circuit, what is the value of current flowing through the diode D2?

a) 0 mA
b) 10 mA
c) 9.3 mA
d) 8.6 mA

Explanation: As the diode D2 is reverse biased, the current flowing through it = 0 mA.

5. In the given circuit, what is the value of the current through the series resistor R2?

a) 9.3 mA
b) 10 mA
c) 0 mA
d) 8.6 mA

Explanation: The voltage across the diodes is 0.7 V as they are forward biased. Hence, the current through the series resistor = (10-0.7)/1k = 9.3 mA.
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6. In the given circuit, what is the current through the parallel resistor?

a) 9.3 mA
b) 0.7 mA
c) 8.6 mA
d) 0 mA

Explanation: As the resistor is in parallel with the diodes, the voltage that appears across it is 0.7 V. Hence, current = 0.7 mA.

7. In the given circuit, what is the value of current through R?

a) 0.7 mA
b) 0.3 mA
c) 1 mA
d) 10 mA

Explanation: The source voltage initially increases from 0-10 V. As the source voltage increases, the voltage across the diodes also increases. When the voltage across the diodes reaches a value of 0.3 V, the Germanium diode starts conducting, whereas the silicon diode is still in the off state. Hence, the voltage across R = 0.3 V. Hence, current = 0.3 mA.

8. In the given circuit, what is the value of current through R2?

a) 9.3 mA
b) 9.7 mA
c) 10 mA
d) 0 mA

Explanation: Here, the voltage across R=0.3 V, hence, current through R2 = (10-0.3) V/ 1 k = 9.7 mA.

9. In the given circuit, what is the value of current through the silicon diode?

a) 9.3 mA
b) 9.7 mA
c) 10 mA
d) 0 mA

Explanation: The source voltage initially increases from 0-10 V. As the source voltage increases, the voltage across the diodes also increases. When the voltage across the diodes reaches a value of 0.3 V, the Germanium diode starts conducting, whereas the silicon diode is still in the off state. Hence, the voltage across silicon diode = 0.3 V and hence, the current according to the approximate equivalent circuit model is equal to zero.

10. In the given circuit, what is the value of current through the germanium diode?

a) 9.4 mA
b) 9.7 mA
c) 0.3 mA
d) 0 mA

Explanation: Current through R2 = 9.7 mA. Also, current through R = 0.3 mA, current through the silicon diode = 0 mA. Hence, from the KCL, we get the current through the germanium diode to be 9.4 mA.

11. In the given circuit, by what amount does the current across R change when the Germanium diode is reconnected in the reverse-bias mode?

a) 0 mA
b) 0.7 mA
c) 0.4 mA
d) 0.3 mA

Explanation: When the germanium diode is forward biased, current through R = 0.3 mA. When the Germanium diode is reverse biased, current through R = 0.7 mA. Hence, change in current = 0.4 mA.

12. In the given circuit, if the diode D2 is a Germanium diode and all other diodes are Silicon diodes, then which of the following statements is true?

a) ID2 < ID3; ID2 = ID1
b) ID2 > ID3; ID2 > ID1
c) ID2 > ID3; ID2 = ID1
d) ID2 > ID3; ID2 < ID1

Explanation: Voltage across the parallel diodes = 0.3 V. Hence, current through D3 = 0. Hence ID2 > ID3. Also, as both the parallel silicon diodes are in parallel and in off-state, the diodes 1 and 2 are in series and hence, current through them is same.

13. In the circuit, considering the diode 1,4 to be a Germanium diode and the diodes 2,3 to be silicon, which of the following statements are true?

a) ID1 = ID2
b) ID1 = ID3
c) ID1 = ID4
d) ID1 > ID4

Explanation: In the given circuit, the silicon diodes are in off-state as the voltage across them is 0.3 V. Hence, they act as open circuit and the diodes 1 and 4 are in series and hence the current through diodes 1 and 4 is same.

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