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Important Questions

Junction Diodes

ICSE · Class 12 · Physics

Most important questions from Junction Diodes for ICSE Class 12 Physics board exam 2026. MCQs, short answer, and long answer questions with marks.

69 questions42 flashcards5 concepts

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A step-by-step diagram illustrating the formation of a p-n junction. Show a p-type and n-type semiconductor brought into contact, followed by the diffusion of majority carriers, the formation of immob
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69 Questions·
multiple choice

Sample Questions

1multiple choice
3 marks

A diode has a peak input voltage of 20 V, a barrier voltage of 0.7 V, a forward resistance of 10 Ω, and a load resistance of 500 Ω. What is the peak current through the circuit?

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37.8 mA

Use V_0 = V_B + I_0(R_F + R_L). Thus I_0 = (20 - 0.7)/(10 + 500) = 19.3/510 = 0.0378 A = 37.8 mA.

2multiple choice
3 marks

A silicon diode with barrier voltage 0.7 V is connected to a 500 Ω load and carries a peak current of 37.8 mA. What is the peak voltage across the load?

Show answer

18.9 V

The load voltage is V_L = I_0R_L = 0.0378 × 500 = 18.9 V.

3multiple choice
3 marks

A Zener diode has V_Z = 12 V and is used with a load resistance of 1 kΩ. If the Zener current is nearly zero, what input voltage is needed when the series resistance is 150 Ω?

Show answer

13.8 V

Load current is I_L = V_Z/R_L = 12/1000 = 12 mA. With I_Z ≈ 0, I = 12 mA. Then V_in = IR + V_Z = 0.012 × 150 + 12 = 1.8 + 12 = 13.8 V.

4multiple choice
3 marks

A Zener regulator has V_Z = 12 V, series resistance 150 Ω, load resistance 1 kΩ, and maximum Zener current 20 mA. What is the maximum input voltage that keeps the output at 12 V?

Show answer

16.8 V

Load current is 12 mA. At maximum Zener current, total current is I = 12 + 20 = 32 mA. Then V_in = IR + V_Z = 0.032 × 150 + 12 = 4.8 + 12 = 16.8 V.

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Frequently Asked Questions

What are the important topics in Junction Diodes for ICSE Class 12 Physics?
Junction Diodes covers several key topics that are frequently asked in ICSE Class 12 board exams. Focus on the core concepts listed on this page and practise related questions to build confidence.
How to score full marks in Junction Diodes — ICSE Class 12 Physics?
Understand the core concepts first, then work through the 69 practice questions available for this chapter. Revise formulas and definitions regularly, and use flashcards for quick recall before the exam.
How many important questions are there in Junction Diodes?
There are 69 practice questions available for Junction Diodes. These cover multiple question types including MCQs, short answer, and long answer questions.

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