Electric Charges and Fields Class 12 Physics PYQs 2026-27
A board-focused practice page combining verified past-paper themes with original PYQ-style questions, answers, worked methods and exam-focused revision.
Class 12 Physics Electric Charges and Fields PYQs for 2026–27
This page is designed for students preparing CBSE Class 12 Physics Chapter 1: Electric Charges and Fields. The current 2026–27 syllabus covers electric charge, Coulomb's law, multiple charges and superposition, continuous charge distribution, electric field and field lines, electric dipole, electric flux and Gauss's law with its standard applications.
How to Use This PYQ Page
- Attempt the PYQ-theme questions from memory and identify the concept tested.
- Solve the original PYQ-style questions without looking at the answers.
- For numericals, write the given values, formula, substitution, unit and final answer.
- For Gauss-law problems, identify the symmetry before choosing the Gaussian surface.
- After practice, revise the linked chapter notes and formula/revision resources.
CBSE PYQ Themes — What Has Been Asked?
CBSE publishes previous-year Class XII question papers through its official question-paper archive. The archive currently provides papers for recent examinations including 2026, 2025 and earlier years.
2025 — Electric Charges and Fields: Reported chapter-wise compilations include questions on interpreting a force-versus-1/r² graph for charges, fields of charge configurations and electric-field properties. These are useful for testing proportional reasoning rather than simple formula recall.
2024 — Electric Charges and Fields: Chapter-wise compilations report questions involving an infinite charged wire, forces in multi-charge systems, electric field at symmetric points, and field/flux applications.
2023 — Electric Charges and Fields: Reported PYQ collections include inverse-square electric-field reasoning, interaction of charged particle beams, and charge/medium-based Coulomb-law questions.
2022 and earlier: Chapter-wise sources report repeated emphasis on Gauss's law, electric dipole field/torque, flux through symmetric surfaces and derivation-based applications.
High-Value PYQ Themes to Master
- Inverse-square dependence and proportionality reasoning
- Coulomb force in different media
- Net electric field due to multiple point charges
- Symmetry at the midpoint, centroid and other special points
- Electric field of an infinite line charge
- Electric field of an infinite plane sheet
- Electric field inside and outside a spherical shell
- Electric flux through a surface or closed Gaussian surface
- Electric dipole field and torque
- Conceptual interpretation of field lines
PYQ-Style Practice Questions
These practice questions are written or reframed for Learn Revise Hub around concepts and reasoning patterns represented in the CBSE syllabus and past-paper themes. They are not presented as verbatim CBSE question-paper reproductions.
Question 1 — Inverse-Square Reasoning
A point charge produces an electric field of magnitude E at distance r. At what distance will the magnitude become E/9?
Answer: 3r
Solution: Since E ∝ 1/r², E′/E = r²/r′² = 1/9. Hence r′ = 3r.
Question 2 — Medium Effect
Two point charges experience force F in vacuum. If the same charges are placed at the same separation in a medium of relative permittivity 4, what is the new force?
Answer: F/4
Solution: In a medium, the electrostatic force is reduced by the relative permittivity: Fm = F/εr = F/4.
Question 3 — Null Point Between Like Charges
Two equal positive point charges are separated by distance d. Where is the net electric field zero on the line joining them?
Answer: At the midpoint.
Solution: At the midpoint the two fields have equal magnitude and opposite directions, so they cancel.
Question 4 — Unlike Charges at the Midpoint
Two equal and opposite point charges are separated by distance d. What is the direction of the net electric field at the midpoint?
Answer: From the positive charge towards the negative charge.
Solution: At the midpoint, the field due to the positive charge points away from it and the field due to the negative charge points towards it. Both therefore point in the same direction.
Question 5 — Electric Field and Potential
At a point, the electric potential is zero. Can the electric field at that point be non-zero?
Answer: Yes.
Solution: Potential is a scalar value, while electric field depends on the spatial variation of potential. For example, cancellation of potentials from different charges does not necessarily cancel their fields.
Question 6 — Electric Flux
A uniform electric field of magnitude E passes through a plane surface of area A. The field makes an angle 60° with the area vector. Find the flux.
Answer: EA/2
Solution: Φ = EA cos 60° = EA/2.
Question 7 — Flux Through a Cube
A point charge q is placed at the centre of a cube. What is the electric flux through each face?
Answer: q/(6ε0)
Solution: Total flux through the cube is q/ε0. Symmetry distributes it equally among six faces.
Question 8 — Infinite Line Charge
An infinitely long straight wire has uniform linear charge density λ. What is the electric field at distance r from the wire?
Answer: E = λ/(2πε0r)
Solution: Use a cylindrical Gaussian surface of radius r and length L. Gauss's law gives E(2πrL) = λL/ε0.
Question 9 — Infinite Plane Sheet
An ideal infinite plane sheet has uniform surface charge density σ. What is the electric field magnitude on either side?
Answer: σ/(2ε0)
Solution: A pillbox Gaussian surface gives 2EA = σA/ε0, hence E = σ/(2ε0).
Question 10 — Spherical Shell
A uniformly charged thin spherical shell carries total charge Q. What is the electric field at a point inside the shell?
Answer: Zero.
Solution: A spherical Gaussian surface entirely inside the shell encloses zero charge. Spherical symmetry then gives zero electric field in the interior region.
Question 11 — Dipole Torque
An electric dipole of moment p is placed in a uniform electric field E at 30°. Find the torque magnitude.
Answer: pE/2
Solution: τ = pE sin 30° = pE/2.
Question 12 — Dipole Equilibrium
At what orientations does the torque on an electric dipole in a uniform electric field become zero?
Answer: θ = 0° and 180°.
Solution: τ = pE sin θ. The sine is zero at 0° and 180°.
Question 13 — Superposition
Three point charges are present in space. Is it valid to calculate the electric field due to each charge separately and then add the fields vectorially?
Answer: Yes.
Solution: Electric fields obey the principle of superposition, so the net field is the vector sum of the individual fields.
Question 14 — Gaussian Surface
Does changing the shape of a closed Gaussian surface change the net electric flux if the net charge enclosed remains unchanged?
Answer: No.
Solution: Gauss's law gives Φ = qenclosed/ε0. The net flux depends on the enclosed charge, not the shape of the closed surface.
Question 15 — Zero Net Flux
A closed surface has zero net electric flux. Does this necessarily mean the electric field is zero everywhere on the surface?
Answer: No.
Solution: Zero net flux means the total surface integral is zero. The field may be non-zero at individual points while positive and negative flux contributions cancel.
Question 16 — Charge Quantisation
A body has charge 3.2 × 10−19 C. Is this charge consistent with charge quantisation? Take e = 1.6 × 10−19 C.
Answer: Yes; it corresponds to 2e.
Solution: q/e = (3.2 × 10−19)/(1.6 × 10−19) = 2, an integer.
Question 17 — Field-Line Concept
Why can two electrostatic field lines not cross at a point?
Answer: Because the electric field at a point has a unique direction.
Solution: If two field lines crossed, the tangent at the intersection would imply two directions for the same electric field, which is impossible.
Question 18 — Continuous Charge Distribution
How is the electric field of a continuous charge distribution calculated using superposition?
Answer: By integrating the contributions of infinitesimal charge elements.
Solution: Divide the distribution into elements dq, write the field contribution dE from each element, and integrate over the complete distribution.
Question 19 — Shell Outside
A point lies outside a uniformly charged thin spherical shell of total charge Q at distance r from its centre. What is the field magnitude?
Answer: E = (1/4πε0)Q/r²
Solution: For an external spherical Gaussian surface, the shell behaves as if its total charge were concentrated at the centre.
Question 20 — Field of a Point Charge
The electric field of a point charge is E at distance r. What is the field at distance 2r?
Answer: E/4
Solution: Since E ∝ 1/r², doubling r reduces the field to one-fourth.
Board-Level Mixed Practice
Question 21 — Multiple Charges
Two charges +q and +4q are separated by distance d. At what point between them is the net electric field zero?
Answer: At a distance d/3 from the +q charge.
Solution: Let the point be x from +q. Equating magnitudes, kq/x² = k(4q)/(d−x)². Thus d−x = 2x, giving x = d/3.
Question 22 — Flux and Area Vector
A field is parallel to a plane surface. What is the electric flux through the surface?
Answer: Zero.
Solution: The area vector is perpendicular to the surface, so the angle between E and A is 90°. Hence Φ = EA cos 90° = 0.
Question 23 — Dipole Field Direction
For a short electric dipole, what is the direction of the electric field on its equatorial line relative to the dipole moment?
Answer: Opposite to the dipole moment.
Solution: The transverse components of the fields from the two charges combine to give a field directed opposite to the dipole moment on the equatorial line.
Question 24 — Gauss's Law Limitation
Is Gauss's law valid only for spherical surfaces?
Answer: No.
Solution: Gauss's law is valid for every closed surface. Symmetric surfaces are chosen because they make the calculation of electric field easier.
Quick Answer Key
| Q | Answer | Q | Answer | Q | Answer |
|---|---|---|---|---|---|
| 1 | 3r | 9 | σ/(2ε0) | 17 | Unique field direction |
| 2 | F/4 | 10 | 0 | 18 | Integrate dE |
| 3 | Midpoint | 11 | pE/2 | 19 | kQ/r² |
| 4 | + to − | 12 | 0°, 180° | 20 | E/4 |
| 5 | Yes | 13 | Vector sum | 21 | d/3 from +q |
| 6 | EA/2 | 14 | No | 22 | 0 |
| 7 | q/(6ε0) | 15 | No | 23 | Opposite to p |
| 8 | λ/(2πε0r) | 16 | 2e | 24 | No |
Most Important Formulas for PYQ Practice
- Coulomb's law: F = (1/4πε) |q₁q₂|/r²
- Point-charge field: E = (1/4πε) |q|/r²
- Superposition: Enet = ΣEi
- Dipole moment: p = qd
- Dipole torque: τ = pE sin θ
- Flux: Φ = EA cos θ
- Gauss's law: Φ = qenclosed/ε0
- Infinite line charge: E = λ/(2πε0r)
- Infinite plane sheet: E = σ/(2ε0)
- Thin spherical shell: E = 0 inside; outside E = (1/4πε0)Q/r²
Common PYQ Mistakes to Avoid
- Using the angle with the surface instead of the angle with the area vector in Φ = EA cos θ.
- Assuming zero potential automatically means zero electric field.
- Forgetting that electric field and force are vectors.
- Using Gauss's law without identifying the symmetry needed to extract E.
- Confusing zero net flux with zero electric field everywhere.
- Forgetting the effect of the medium on Coulomb's law.
- Giving only a formula when a board question asks for a derivation or reasoning.
Chapter Resources
Continue the chapter sequence:
Research basis: CBSE 2026–27 Physics curriculum and the official CBSE previous-year question-paper archive were used to establish the current chapter scope and PYQ research framework. Past-paper themes have been paraphrased rather than presented as a claim that the wording below is an official CBSE reproduction.
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