P-N Junction Diode and its applications – Page 2 – Rankers Physics
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P-N Junction Diode and its applications

Question 1:

In the following circuit the equivalent resistance between A and B is

20/3 Ω
10 Ω
16 Ω
20 Ω
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Solution:

Both the diodes are reversed biased so can be replaced by open circuit.

Req= 8+2+6= 16 ohm

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Question 2:

If break down voltage of zener diode is 6 V then value of I2 will be :

 

18 mA
24 mA
6 mA
Zero
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Solution:

Voltage across 500 ohm resistor = 12 Volt

I = 12/500 = 24 mA

I 1 =  6/1000= 6mA

I2= I - I1= (24-6 )mA= 18 mA

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Question 3:

Determine V0 for the network

6.6 V
9 V
-9 V
-6.6 V
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Solution:

Both the diodes are forward biased so current will flow through the circuit

i= 10/4.5= 20/9 mA

V0= i R= (20/9)×3.3 Volt= 6.6 volt

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Question 4:

When a PN junction diode is reverse biased :

Electrons and holes are attracted towards each other and move towards the depletion region
Electrons and holes move away from the junction depletion region
Height of the potential barrier decreases
No change in the current takes place
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Solution:

Factual Question: When a PN junction diode is reverse biased potential barrier of depletion increases. Thus Electrons and holes move away from the junction depletion region.

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Question 5:

Two PN-junctions can be connected in series by three different methods as shown in the figure. If the potential difference in the junctions is the same, then the correct connections will be :

In the circuit (1) and (2)
In the circuit (2) and (3)
In the circuit (1) and (3)
Only in the circuit (1)
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Solution:

In circuit 1. First Diode is forward biased and second diode is reverse biased. So, potential across 1st diode is less than 2nd diode.

In circuit 2: Both the diodes are forward biased so potential difference across them is equal

In circuit 3: Both the diodes are reverse biased so potential difference across them is equal to V/2.

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Question 6:

The dominant mechanism for motion of charge carriers in forward and reverse biased silicon P-N junction are :

Drift in forward bias, diffusion in reverse bias
Diffusion in forward bias, drift in reverse bias
Diffusion in both forward and reverse bias
Drift in both forward and reverse bias
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Solution:

Theory: In forward biased mode diffusion current is more than drift current. Where as in reverse biased mode diffusion current decreased and become less than drift current.

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Question 7:

In the given circuit

The current through the battery is :

0.5 A
1 A
1.5 A
2 A
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Solution:

Diode D2 and D3 are forward biased. Where as Diode D1 is reversed biased. No current will flow through D1. 

Equivalent Resistance= 20/3 ohm

Current = Voltage / Resistance = 10/ (20/3) = 1.5 Ampere

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Question 8:

Phodiode, zenerdiode and solar cell is used in:

Forward Bias, Reverse Bias, Forward Bias
Reverse Bias, Reverse Bias, Unbiased
Reverse Bias, UnBias, Reverse Bias
Reverse Bias, Reverse Bias, Reverse Bias
View Solution

Solution:

A Photodiode and Zener Diode operate in Reverse Bias, while a Solar Cell operates in an Unbiased condition (zero external voltage).

  • Photodiode: Works in reverse bias to detect light.
  • Zener Diode: Operates in reverse bias for voltage regulation.
  • Solar Cell: Generates power in an unbiased condition when exposed to light.

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