Скачать или смотреть A zener diode with 5V zener voltage is used to regulate an unregulated dc voltage input of 25 V. For

A zener diode with 5V zener voltage is used to regulate an unregulated dc voltage input of 25 V. For a 400 Ω resistor connected in series, the zener
current is found to be 4 times load current. The load current (IL) and load resistance (RL) are :
(1) IL = 20 mA; RL = 250 Ω
(2) IL = 10 A; RL = 0.5 Ω
(3) IL = 0.02 mA; RL = 250 Ω
(4) IL = 10 mA; RL = 500 Ω

🔌 JEE MAINS 2025 PHYSICS | ZENER DIODE AS VOLTAGE REGULATOR ⚡

Chapter: Semiconductor Electronics
Topic: Zener Diode & Voltage Regulation

In this video, I have explained a highly important JEE Mains 2025 Physics problem based on the application of Zener diode as a voltage regulator 🔋✨. Questions like this are extremely common in both January and April attempts, as NTA frequently tests practical understanding of semiconductor devices.

🧠 Core Concept Behind This Problem:

A Zener diode is specially designed to operate in the reverse breakdown region, where it maintains a constant output voltage even when the input voltage changes. This makes it an ideal component for voltage regulation in electronic circuits 📟.

In this question:

An unregulated DC input is given

A series resistor controls the current

The Zener diode ensures a fixed output voltage across the load

The relationship between Zener current and load current is clearly specified

Such details indicate that the problem is testing conceptual clarity of current distribution in a regulated circuit rather than numerical complexity.

🔍 Important Theory Points Covered:

🔹 Voltage Regulation Principle
The Zener diode absorbs extra current when the load current changes, ensuring that the voltage across the load remains constant.

🔹 Role of Series Resistor
The series resistor protects the Zener diode and controls the total current supplied by the source.

🔹 Current Sharing Concept
The total current from the source splits into:

Current through the Zener diode

Current through the load

Understanding how these currents relate to each other is the key idea tested in this problem ⚡.

🔹 Why This Is High-Scoring for JEE Mains
✅ Direct NCERT-based concept
✅ No lengthy derivations
✅ Real-life electronics application
✅ Frequently repeated in PYQs

🎯 Exam Relevance (April Attempt Focus):

📌 Semiconductor Electronics is a low-effort, high-return chapter
📌 Such regulator questions are often straightforward if theory is clear
📌 Ideal for quick marks under time pressure

This problem strengthens understanding of diodes, current control, and practical circuits, which are essential for JEE Mains 2025 aspirants aiming for a high percentile 🚀.

📚 Watch this video to build strong conceptual foundations in Zener diode regulation, avoid common mistakes, and approach similar JEE questions with confidence 💯.

🔔 Stay tuned for more exam-oriented Physics explanations.

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