NCERT Class 12 Physics Chapter 2: Updated facts (Apr 23, 2026)
NCERT Class 12 Physics Chapter 2 solutions were updated on Apr 23, 2026 to highlight formulas, repeated questions and exam weightage. The chapter on electrostatic potential and capacitance carries 7–8 marks in CBSE boards and typically supplies 2–3 questions per shift in JEE/NEET papers according to past papers.
NCERT Class 12 Physics Chapter 2: Key formulas students must memorise
Capacitance of a parallel-plate capacitor: C = ε0 A / d. With a dielectric, C' = K ε0 A / d — capacitance increases by factor K.
Energy stored in a capacitor: U = Q² / 2C = ½ C V² = ½ Q V. Energy density in the field: u = ½ ε0 E². Relation between field and potential: E = −dV/dr.
Potential inside a hollow conducting sphere of radius R: Vinside = Vsurface = kQ/R (constant since E = 0 inside). Van de Graaff generators can reach potentials of order 10^6 V and are used as particle accelerators in nuclear experiments.
NCERT Class 12 Physics Chapter 2: What appears most in exams
These topics recur in board and competitive papers:
| Topic | Frequency (last 5 years) |
|---|---|
| Energy stored in capacitor | 5/5 years |
| Equipotential surfaces | 5/5 years |
| Capacitance (parallel-plate) | 4/5 years |
| Dielectric effects | 4/5 years |
| Van de Graaff generator | 3/5 years |
Repeated question years for the parallel-plate derivation include 2017, 2019, 2022, 2024 . Energy-stored questions appeared in 2015, 2018, 2020, 2023, 2025 . Equipotential surfaces and hollow-sphere potential have also been frequent.
Quick study facts and timing
You can cover the chapter for board preparation in 10–12 hours using concise notes and solved problems designed to match the CBSE marking scheme. Expect 4–5 questions from this chapter in a typical paper, totalling about 7–9 marks .
Focus on clear, labelled diagrams for equipotential surfaces and the Van de Graaff generator, and practise derivations stepwise — these are commonly tested and carry marks.
FAQs
What is electrostatic potential as defined in NCERT?
Work done per unit positive charge bringing it from infinity to the point; SI unit volt (V).
What are equipotential surfaces?
Surfaces where every point has the same potential. No work is done moving a charge along them.
What is the relation between electric field and potential?
Electric field E is the negative gradient of potential: E = −dV/dr.
What is the expression for potential due to a point charge?
V = (1/(4πε0)) × (q/r), with potential at infinity taken as zero.
What is a capacitor and its capacitance definition?
A device that stores charge; C = q/V. SI unit is farad (F).
What is the capacitance of a parallel-plate capacitor?
C = ε0 A / d; with a dielectric filling the gap C = K ε0 A / d.
What is the energy stored in a capacitor?
U = ½ C V² = Q² / (2C) = ½ Q V.
Facts above are based on CBSE past papers and official exam patterns and reflect repeated question trends up to Apr 23, 2026.