Physics Important Questions Class 12 CBSE 2026 — Chapter Wise
Class 12 Physics important questions 2026 — derivations, numericals from electrostatics, optics, and modern physics for CBSE boards.
CBSE Class 12 Physics: 70 marks theory + 30 marks practical. Electrostatics + Current Electricity (16 marks), Optics (14 marks), and Magnetism + EMI (12 marks) cover 60% of the paper. Below are the most expected questions — derivations, numericals, and theory — from each chapter.
Unit-Wise Marks Distribution
| Unit | Chapters | Marks |
|---|---|---|
| Electrostatics & Current Electricity | Electric Charges & Fields, Electrostatic Potential, Current Electricity | 16 |
| Magnetic Effects & EMI | Moving Charges & Magnetism, Magnetism & Matter, EMI, AC | 12 |
| EM Waves | Electromagnetic Waves | 4 |
| Optics | Ray Optics, Wave Optics | 14 |
| Dual Nature & Atoms & Nuclei | Dual Nature of Radiation, Atoms, Nuclei | 12 |
| Electronic Devices | Semiconductor Electronics | 7 |
| Communication Systems | Communication Systems | 5 |
Electrostatics (8 marks)
| Question | Type | Marks |
|---|---|---|
| Derive the expression for electric field on the axial and equatorial line of a dipole. | Derivation | 5 |
| Derive the expression for capacitance of a parallel plate capacitor with and without dielectric. | Derivation | 5 |
| Two point charges of 3μC and −3μC are at distance 20cm. Find electric field and potential at the midpoint. | Numerical | 3 |
| Draw electric field lines for: (a) positive charge, (b) dipole, (c) two positive charges. State 3 properties of field lines. | Diagram + Theory | 3 |
| Explain the principle of a Van de Graaff generator with diagram. | Theory + Diagram | 3 |
| Three capacitors of 2μF, 3μF, 6μF are connected first in series then in parallel. Find equivalent capacitance in each case. | Numerical | 3 |
Current Electricity (8 marks)
| Question | Type | Marks |
|---|---|---|
| State and explain Kirchhoff's rules. Use them to find current in a Wheatstone bridge circuit. | Theory + Numerical | 5 |
| Derive the condition for balance in a Wheatstone bridge. | Derivation | 3 |
| Explain the working of a meter bridge with circuit diagram. How is unknown resistance determined? | Theory + Diagram | 5 |
| A cell of EMF 1.5V and internal resistance 0.5Ω supplies current through a 2Ω external resistor. Find current, terminal voltage, and power dissipated. | Numerical | 3 |
| What is drift velocity? Derive the relation between drift velocity and current: I = nAeVd. | Derivation | 3 |
| Explain the principle of a potentiometer. How is it used to compare EMFs of two cells? | Theory + Diagram | 5 |
Magnetism & EMI (12 marks)
| Question | Type | Marks |
|---|---|---|
| State Biot-Savart law. Derive the expression for magnetic field at the centre of a circular current-carrying loop. | Derivation | 5 |
| State Ampere's circuital law. Use it to find the magnetic field inside a solenoid. | Derivation | 5 |
| Describe the working of a moving coil galvanometer with diagram. How can it be converted to: (a) ammeter, (b) voltmeter? | Theory + Diagram | 5 |
| State Faraday's laws of electromagnetic induction. Explain Lenz's law with example. | Theory | 3 |
| Derive the expression for EMF induced in a rod moving in a magnetic field. | Derivation | 3 |
| Describe the working of an AC generator with labelled diagram. Draw the graph of EMF vs time. | Theory + Diagram | 5 |
| What is a transformer? Explain its working principle and derive the turns ratio. | Theory + Derivation | 3 |
Practise Physics chapter-wise
Super Tutor has chapter-wise Physics questions for Class 12 — numericals, derivations, and theory. Practise with step-by-step solutions.
Start Physics Practice — FreeOptics (14 marks)
| Question | Type | Marks |
|---|---|---|
| Derive the lens maker's equation: 1/f = (n−1)(1/R₁ − 1/R₂). | Derivation | 5 |
| Draw a ray diagram for image formation by a compound microscope. Derive the expression for magnifying power. | Diagram + Derivation | 5 |
| Explain total internal reflection. State 2 conditions. Give 2 applications (optical fibre, mirage). | Theory | 3 |
| Derive the expression for refraction at a spherical surface: n₂/v − n₁/u = (n₂−n₁)/R. | Derivation | 5 |
| Describe Young's double slit experiment. Derive the expression for fringe width: β = λD/d. | Derivation | 5 |
| What is diffraction of light? Compare interference and diffraction patterns. | Theory | 3 |
| A convex lens of focal length 20cm is placed in contact with a concave lens of focal length 25cm. Find the power and focal length of the combination. | Numerical | 2 |
| State Brewster's law. At what angle is reflected light completely polarised for glass (n=1.5)? | Theory + Numerical | 3 |
Modern Physics (12 marks)
| Question | Type | Marks |
|---|---|---|
| State the laws of photoelectric emission. Explain Einstein's photoelectric equation: Kmax = hν − φ. | Theory | 5 |
| The work function of a metal is 2.5 eV. Find threshold frequency and max KE of photoelectrons if light of 6×10¹⁴ Hz falls on it. | Numerical | 3 |
| Derive the expression for de Broglie wavelength: λ = h/mv. Calculate for an electron accelerated through 100V. | Derivation + Numerical | 3 |
| Using Bohr's postulates, derive the expression for the radius of nth orbit and energy of electron in hydrogen atom. | Derivation | 5 |
| Draw the energy level diagram for hydrogen. Calculate the wavelength of the first line of the Balmer series. | Diagram + Numerical | 3 |
| What is nuclear fission and nuclear fusion? Why is fusion difficult to achieve? Compare the two. | Theory | 3 |
| Define half-life and decay constant. Derive the relation: T½ = 0.693/λ. | Derivation | 3 |
| What is binding energy per nucleon? Draw the BE/A vs mass number graph. What does it indicate about nuclear stability? | Theory + Graph | 3 |
Semiconductor Electronics (7 marks)
| Question | Type | Marks |
|---|---|---|
| Explain forward and reverse bias of a p-n junction with circuit diagram and V-I characteristics. | Theory + Diagram | 5 |
| Draw the circuit diagram of a full-wave rectifier. Explain its working with input/output waveforms. | Diagram + Theory | 5 |
| Draw the truth tables and logic symbols for AND, OR, NOT, NAND, NOR gates. | Diagram | 3 |
| Show that NAND gate is a universal gate (construct AND, OR, NOT using NAND gates). | Diagram + Theory | 3 |
Must-Know Derivations Summary
| Derivation | Chapter | Priority |
|---|---|---|
| Electric field due to dipole (axial + equatorial) | Electrostatics | Very High |
| Capacitance of parallel plate capacitor | Electrostatics | High |
| Biot-Savart: field at centre of circular loop | Magnetism | Very High |
| Ampere's law: field inside solenoid | Magnetism | High |
| Lens maker's equation | Ray Optics | Very High |
| Young's double slit: fringe width | Wave Optics | Very High |
| Bohr model: radius and energy | Atoms | High |
| de Broglie wavelength | Dual Nature | High |
Questions based on analysis of CBSE Class 12 Physics papers (2018–2025) and 2026 sample paper. Marks from CBSE 2025–2026 blueprint. Complete NCERT thoroughly before using this as a revision guide. Last updated: February 2026.
Turn this into board-exam marks
Super Tutor gives you chapter summaries, previous-year questions, and full mock exams matched to your board syllabus — so you revise smarter, not longer.
Start preparing — freeFrequently Asked Questions
Which chapters are most important for Class 12 Physics?
Top 3 by marks: Electrostatics + Current Electricity (16 marks), Optics (14 marks), Magnetism + EMI (12 marks). These 3 units cover 60% of the 70-mark theory paper. Modern Physics (Dual Nature + Atoms + Nuclei) carries 12 marks and is relatively easy.
How many derivations are asked in Physics board exam?
Typically 2-3 derivations in the 5-mark long answer section. Must-know: electric field due to dipole, Biot-Savart law for circular loop, lens maker's equation, Young's double slit fringe width, and Bohr model energy levels. Each derivation should include a diagram.
Are numericals important in Class 12 Physics?
Very important — 25-30 marks (out of 70) are numerical-based. Electricity (Ohm's law, Kirchhoff's, Wheatstone bridge), Optics (mirror/lens formula, power), and Modern Physics (photoelectric effect, de Broglie) are the most numerical-heavy chapters.
How to prepare Physics in the last month?
Focus on: (1) Revise all formulas daily (15 min). (2) Practise 10 numericals per day. (3) Write 1 derivation from memory daily. (4) Solve 1 sample paper every 3 days. (5) Draw and label all diagrams. Physics rewards consistent practice over last-minute cramming.