Class 12 PhysicsImportant Questions for Board Exams 2025-26
21
Total Questions
17
Long Answer
4
Short Answer
Electric Charges and Fields
2 questionsState and prove Gauss's law. Apply it to find the electric field due to an infinitely long straight wire.
Derive an expression for the electric field on the equatorial line of an electric dipole.
Electrostatic Potential and Capacitance
1 questionsDerive the expression for the energy stored in a parallel plate capacitor. What happens when a dielectric slab is inserted?
Current Electricity
2 questionsState Kirchhoff's laws. Using them, find the current in each branch of a given circuit.
Derive the condition for balance of a Wheatstone bridge.
Moving Charges and Magnetism
1 questionsState Biot-Savart law. Use it to find the magnetic field at the centre of a circular current loop.
Magnetism and Matter
1 questionsDistinguish between diamagnetic, paramagnetic and ferromagnetic substances. Give one example of each.
Electromagnetic Induction
1 questionsState Faraday's laws of electromagnetic induction. Derive an expression for motional EMF.
Alternating Current
2 questionsDerive an expression for the impedance of a series LCR circuit. Define resonance and Q-factor.
An LCR circuit has L = 0.1H, C = 25μF, R = 10Ω. Find the resonant frequency.
Electromagnetic Waves
2 questionsWhat is displacement current? Why did Maxwell introduce it?
Describe the electromagnetic spectrum. Give one use of each type of radiation.
Ray Optics and Optical Instruments
1 questionsDraw a ray diagram for a compound microscope when the final image is at infinity. Derive the expression for magnifying power.
Wave Optics
1 questionsIn Young's double slit experiment, derive the expression for fringe width. What happens to the fringe width if: (i) wavelength is increased (ii) slit separation is increased?
Dual Nature of Radiation and Matter
2 questionsExplain the photoelectric effect. Write Einstein's photoelectric equation and explain each term.
Calculate the de Broglie wavelength of an electron accelerated through 100V.
Atoms
1 questionsState Bohr's postulates. Derive the expression for the radius of the nth orbit of hydrogen atom.
Nuclei
2 questionsWhat is binding energy? Draw a binding energy per nucleon vs mass number graph and explain its features.
The half life of a radioactive isotope is 5 years. How much of 100g remains after 20 years?
Semiconductor Electronics
2 questionsExplain the working of a p-n junction diode as a full wave rectifier with a circuit diagram and waveform.
Draw the truth table for NAND and NOR gates. Why are they called universal gates?
Frequently Asked Questions
Which are the most important questions in Class 12 Physics for CBSE board exam?
All 21 questions listed here are selected based on CBSE board exam frequency and marks weightage. Prioritise long-answer (5-mark) questions first — 17 questions here — as they carry the most marks. Short-answer questions (4 here) are next. Together they cover the questions most likely to appear.
Is it enough to study only important questions for CBSE Class 12 Physics?
Practising these 21 important questions gets you to 70–75% marks. For 85%+, also read chapter summaries and attempt at least one full sample paper under timed conditions. Use these important questions as your minimum baseline, not your ceiling.
How should I write answers in CBSE Class 12 Physics board exam?
For 1-mark questions: one direct sentence — no elaboration needed. For 3-mark questions: 3 clearly numbered points, each 1–2 lines. For 5-mark questions: brief intro + 4–5 numbered points with subject-specific keywords + 1-line conclusion. CBSE examiners look for keywords in marking schemes — structure your answers around them.
How many questions come from each chapter in Class 12 Physics CBSE board exam?
CBSE doesn't publish a fixed chapter-wise distribution, but chapters with more important questions listed here have historically appeared more frequently in board papers. Focus extra time on chapters with 5 or more questions — those chapters consistently carry high marks.