Electric Charges and FieldsNEET MCQs with solutions
Electric Charges and Fields covers Coulomb's law, electric field, electric flux, Gauss's law and electric dipoles. NEET tests Coulomb's law numericals, electric field due to various charge distributions, Gauss's law application and dipole field/torque — both conceptual and numerical questions.
- Class
- 12 Physics
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- 24 questions
- In the RankUp app
- 643 questions
- ELITE questions
- 270
- NCERT topics
- 14
Practise 24 questions
Tap an option to check it. Questions from every NCERT topic in this chapter, from easy to hard.
Q1Mixed Revision
A charge +Q is placed at the centre of a spherical Gaussian surface. If the radius of the sphere is doubled, the total electric flux through the surface becomes:
Not quite — the answer is C.
Gauss's law: flux = q_enclosed/ε₀, depends only on enclosed charge, not on size or shape of surface. Doubling radius does not change enclosed charge. Option A is wrong — radius change has no effect on flux.
Q2Electric Flux
The SI unit of electric flux is:
Not quite — the answer is C.
Φ = E·A gives units (N/C)(m²) = N·m²/C. Option A is unit of E alone; Option B misses one power of metre; Option D is surface charge density.
Q3Coulomb's Law
Coulomb's law is applicable when the interacting charges are:
Not quite — the answer is A.
Coulomb's law is valid for stationary point charges. Moving charges require full electromagnetic treatment; current conductors involve drift velocity, not static charges.
Q4Gauss's Law
Gauss's law states that the total electric flux through any closed surface is equal to:
Not quite — the answer is B.
Gauss's law: net electric flux = Q_enc/ε₀. Only charges enclosed by the surface contribute; external charges produce zero net flux. Option C is the named trap: student incorrectly includes all charges regardless of position.
Q5Electric Field
The SI unit of electric field intensity is:
Not quite — the answer is B.
Electric field E = F/q gives units of N/C, equivalently written as V/m. Option A (C/N) inverts the ratio; options C and D are dimensionally incorrect combinations.
Q6Grand Test
A dipole of moment 4×10⁻⁸ C·m is placed perpendicular to a uniform electric field of 5×10⁵ N/C. The torque acting on the dipole is:
Not quite — the answer is C.
τ = pE sinθ. At θ=90°, sinθ=1: τ = 4×10⁻⁸×5×10⁵ = 2×10⁻² N·m. Option D (zero) is the stable-equilibrium trap — applies only at θ=0°, not θ=90°.
Q7Forces Between Multiple Charges & Superposition Principle
Three charges +2 μC, +3 μC and −5 μC are placed at vertices of an equilateral triangle. The net force on +2 μC is obtained by:
Not quite — the answer is B.
Superposition principle: each force is calculated independently via Coulomb's law, then added vectorially. Magnitude-only addition (Option A) ignores direction and gives wrong results for non-collinear forces.
Q8Applications of Gauss's Law (Infinite Plane Sheet of Charge)
The electric field due to an infinite plane sheet having uniform surface charge density σ is:
Not quite — the answer is A.
A pillbox Gaussian surface of area A straddles the sheet. Flux exits both flat faces: 2EA = σA/ε₀, giving E = σ/(2ε₀). Option B is the conducting-sheet result — the most dangerous distractor at this level.
Q9Electric Dipole
Consider the following statements about an electric dipole: I. The net charge of a dipole is always zero. II. The dipole moment is a scalar quantity. III. Dipole moment depends on both charge magnitude and separation. IV. A single isolated charge can act as a dipole. How many of the above statements are CORRECT?
Not quite — the answer is B.
Net charge is zero (I true). Dipole moment p = qd is a vector, not scalar (II false). p depends on q and d (III true). A single charge has no separation, so cannot form a dipole (IV false). Only I and III are correct.
Q10Applications of Gauss's Law (Infinite Line Charge)
An infinitely long straight wire has uniform linear charge density λ. The electric field at a perpendicular distance r from the wire is:
Not quite — the answer is B.
A cylindrical Gaussian surface of radius r and length L gives enclosed charge λL. Flux passes only through curved surface: E(2πrL) = λL/ε₀, so E = λ/(2πε₀r). Option A is the point-charge formula with r, a common substitution error.
Q11Properties of Electric Charge
Which of the following is NOT a fundamental property of electric charge?
Not quite — the answer is D.
NCERT lists exactly three fundamental properties of charge: conservation, quantisation, and additivity. Polarisation is charge redistribution under an external field — a consequence of these properties, not a property itself.
Q12Introduction to Electric Charge
Which of the following is the correct SI unit of electric charge?
Not quite — the answer is B.
Charge is measured in coulomb (C); 1 C is charge transported by 1 A in 1 s. Farad is unit of capacitance, Ampere of current, Volt of potential difference.
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Get RankUp on Google PlayQ13Applications of Gauss's Law
A solid conducting sphere carries charge +Q. The electric field inside the conductor in electrostatic equilibrium is:
Not quite — the answer is B.
In electrostatic equilibrium, excess charge resides on the outer surface; the interior has no net charge, so E = 0 everywhere inside by Gauss's law. Options A, C, D all incorrectly assign a non-zero interior field.
Q14Electric Field Lines
The number of electric field lines drawn from a charge is proportional to:
Not quite — the answer is A.
The number of field lines is proportional to the magnitude of charge. A charge 2q has twice the field lines of charge q. Sign determines direction, not count.
Q15Introduction to Electric Charge
A body possesses a net charge of +4.8 × 10⁻¹⁹ C. The minimum number of electrons removed from the body is:
Not quite — the answer is C.
Positive charge indicates electron removal. n = q/e = (4.8×10⁻¹⁹)/(1.6×10⁻¹⁹) = 3. Option A (n=2) gives only 3.2×10⁻¹⁹ C, which does not match. Quantisation: q = ne.
Q16Introduction to Electric Charge
Which of the following best describes charge conservation in an isolated system?
Not quite — the answer is A.
The Law of Conservation of Charge: total charge of an isolated system is constant. Charges are only transferred, never created or destroyed. This applies to all materials, not conductors alone.
Q17Introduction to Electric Charge
Which of the following statements about electric charge is INCORRECT?
Not quite — the answer is D.
A charged body has excess or deficiency of electrons but still contains both protons and electrons. Net charge is non-zero, but both charge types coexist. Options A, B, C are all fundamental NCERT properties of charge.
Q18Introduction to Electric Charge
A current of 2 A flows through a conductor for 5 s. The total charge passing through any cross-section is:
Not quite — the answer is D.
Q = It = 2 × 5 = 10 C. A common error is dividing: Q = I/t = 0.4 C (Option A trap). Current is charge per unit time, so charge = current × time.
Q19Introduction to Electric Charge
In charging by induction, which of the following is the CORRECT sequence to give a metal sphere a positive charge using a negatively charged rod?
Not quite — the answer is B.
The rod repels electrons in the sphere to earth. Removing earthing first traps the electron deficiency. Removing the rod last leaves the sphere positive. Option A (conduction) gives negative charge. Option C earths after rod removal — no redistribution occurs.
Q20Introduction to Electric Charge
Which of the following correctly represents the quantisation of electric charge at the NCERT level?
Not quite — the answer is A.
Charge quantisation: q = ne, n is any integer (positive, negative; n = 0 means neutral, not a "charged" body). Option C is a subtle trap — n = 0 is mathematically valid but the formula applies to charged bodies per NCERT context. Option B and D are dimensionally or conceptually wrong.
Q21Introduction to Electric Charge
A glass rod rubbed with silk becomes positively charged because:
Not quite — the answer is C.
Rubbing transfers electrons from the glass rod to silk. Protons are tightly bound inside atomic nuclei and cannot be transferred. The glass rod, having lost electrons, acquires net positive charge.
Q22Introduction to Electric Charge
Which of the following quantities remains unchanged during charging by friction?
Not quite — the answer is B.
During friction, individual bodies become oppositely charged, but total charge of the isolated system is conserved. A common error is selecting "charge on each body" — each body's charge changes sign and magnitude; only the total is constant.
Q23Introduction to Electric Charge
Two small identical metal bodies carry charges of +3e and −5e. They are brought into contact and then separated. The charge on each body after separation is:
Not quite — the answer is A.
Total charge = +3e + (−5e) = −2e. Distributed equally between identical bodies: each gets −e. Option D (−2e each) is a common trap — students forget to divide by 2. Illustrates additivity and conservation.
Q24Introduction to Electric Charge
A neutral metal sphere is given a positive charge by induction (earthing removed first, then rod removed). Which statement correctly describes the final charge on the sphere?
Not quite — the answer is C.
Induction with a negative rod pushes electrons to earth. Removing earthing first traps the electron deficiency. Removing the rod leaves the sphere with net positive charge. Option B (negative) is the error when students assume sphere takes sign of the rod.
ELITE question · AIR under 50 level
This chapter has 270 ELITE questions for students aiming at the very top. They are only in the app.
Unlock ELITE questions in the appKey Electrostatics Concepts
Quick revision: most questions in this chapter test these facts.
| Concept | Key Formula |
|---|---|
| Coulomb's law | F = kq₁q₂/r²; k = 9 × 10⁹ N m² C⁻² |
| Electric field | E = F/q₀ = kQ/r²; direction: away from +, towards − |
| Gauss's law | ∮E·dA = q_enc/ε₀; useful for symmetric charge distributions |
| Dipole moment | p = qd; torque τ = p × E = pE sinθ |
| Field on axis of dipole | E = 2kp/r³ (far field); on equatorial: E = kp/r³ |
| Electric flux | Φ = E·A = EA cosθ; total flux through closed surface = q/ε₀ |
What the app covers in this chapter
643 questions in total, each with a detailed explanation.
| Mixed Revision | 108 |
| Electric Flux | 59 |
| Coulomb's Law | 56 |
| Gauss's Law | 56 |
| Electric Field | 55 |
| Grand Test | 55 |
| Forces Between Multiple Charges & Superposition Principle | 40 |
| Applications of Gauss's Law (Infinite Plane Sheet of Charge) | 40 |
| Electric Dipole | 39 |
| Applications of Gauss's Law (Infinite Line Charge) | 39 |
| Properties of Electric Charge | 38 |
| Introduction to Electric Charge | 20 |
| Applications of Gauss's Law | 20 |
| Electric Field Lines | 18 |
Questions students ask
Is Electric Charges and Fields important for NEET?
Very important — Coulomb's law, electric field calculations, Gauss's law and dipole problems are tested every year. It is the foundation of electrostatics.
Which topics should I revise first?
Master Coulomb's law with superposition, electric field due to point charges and dipoles, Gauss's law for sphere/cylinder/plane, and dipole torque and potential energy in uniform field.
How many questions from this chapter are on RankUp?
The RankUp app has 643 questions on Electric Charges and Fields, including 270 ELITE questions. Every question has a detailed explanation.
