Electronics is an important branch of physics that deals with semiconductors and electronic devices like diodes, transistors, and logic gates. It explains how electrical signals are controlled and used in modern devices.
This chapter is very important for exams and helps students understand the basic working of digital electronics used in mobiles, computers, and other technologies.
📥 Download Section – Class 12 Physics Chapter 18: Electronics Notes
Skip to PDF content📄 Download Complete Class 12 Physics Chapter 18 – Electronics Notes (Punjab Board 2026)
These notes are fully updated according to the latest syllabus and are perfect for board exam preparation.
👉 Download Link: Click here to download Chapter 18 Electronics Notes
📚 What’s Included in This PDF?
✔ Semiconductors (Intrinsic & Extrinsic)
✔ P-N Junction Diode & Biasing
✔ Rectifiers (Half-wave & Full-wave)
✔ Transistors (NPN & PNP)
✔ Logic Gates: AND, OR, NOT, NAND, NOR, XOR, XNOR
✔ Truth tables of all logic gates
✔ Important MCQs
✔ Short Questions (Exam Based)
📝 MCQs – Class 12 Physics Chapter 18: Electronics
1. A p–n junction is said to be forward biased when:
(a) p-side is negative and n-side is positive
(b) p-side is positive and n-side is negative ✅
(c) both sides are positive
(d) both sides are negative
2. In normal operation of a transistor, the base–emitter junction is:
(a) Reverse biased
(b) Forward biased ✅
(c) Unbiased
(d) Alternately biased
3. The region around the p–n junction where charge carriers are absent is called:
(a) Neutral region
(b) Conducting region
(c) Depletion region ✅
(d) Junction region
4. In half-wave rectification, how many halves of an AC cycle are used?
(a) None
(b) One half ✅
(c) Two halves
(d) Three halves
5. The closed-loop gain of an inverting amplifier depends on:
(a) Open-loop gain
(b) Supply voltage
(c) External resistances R1 and R2 ✅
(d) Frequency of input
6. The number of basic operations in Boolean algebra is:
(a) Two
(b) Three ✅
(c) Four
(d) Five
❓ FAQs – Electronics
Q1: What is Electronics in Physics?
Electronics is the branch of physics that deals with the flow of electrons in semiconductors and electronic devices like diodes, transistors, and logic gates.
Q2: Why is Electronics an important chapter?
It is important because it explains the working of modern devices like mobile phones, computers, and digital circuits. It is also very important for board exams.
Q3: What is a PN junction diode?
A PN junction diode is a semiconductor device that allows current to flow in one direction only.
Q4: What is the main function of a transistor?
A transistor is mainly used for amplification and switching of electronic signals.
Q5: What are logic gates?
Logic gates are basic electronic circuits that perform logical operations like AND, OR, NOT, NAND, NOR, XOR, and XNOR.