Electrostatics — NEET Physics MCQs with answers

Electrostatics is a Class 12 Physics chapter in the NEET (UG) syllabus. NEET720 has 1,047 reviewed practice questions on it, each with a quick answer and a step-by-step explanation. The 8 questions below are free and fixed, so you can bookmark this page; the full chapter, plus mistake tracking and spaced revision, is in the app.

Topics covered

Charge and Coulomb's law · Electric field and field lines · Gauss's law and applications · Electric potential and potential energy · Electric dipole · Conductors and electrostatic shielding · Capacitance and dielectrics · Capacitor combinations and energy · Electrostatic Potential · Coulomb's Law and Fields · Electric flux · Electrostatics of conductors · Equipotential Surfaces · Conductors in Electrostatics · Van de Graaff Generator · Common Potential · Potential energy · Electric Potential · Conductors · Gauss's Law · Capacitors · Electric Field · Coulomb's Law · Dipole · Capacitors in Combination · Coulomb's Law and Field · Electrostatics Overview · Capacitance · Electric Potential Energy · Electroscope observations · Charging by induction · Capacitor combinations · Electric charge · Electric field lines · Applications · Dielectrics · Work and potential · Capacitor networks · Electrostatic PE of system · Coulomb force

8 free Electrostatics practice questions with answers

Choose an answer in your head before opening it. Each explanation says why the correct option is right and, where relevant, why the tempting wrong option is wrong.

1. Question 1 · easy · Capacitance and dielectrics

   A dielectric slab placed inside a uniform electric field between capacitor plates develops surface charges of its own. This phenomenon is called:

   • A.electrostatic shielding
   • B.electromagnetic induction
   • C.polarisation
   • D.corona discharge
   Show answer and explanation

   Answer: C. polarisation

   The alignment of molecular dipoles in a dielectric under an external field, producing bound surface charges, is called polarisation.

   When a dielectric is placed in an external electric field, its constituent molecules (or induced dipoles) align with the field, producing bound charges on the dielectric's surfaces. This is called polarisation, and the resulting internal field opposes the external field, reducing the net field inside the dielectric. This is distinct from electrostatic shielding (field-free cavity inside a conductor) and unrelated to electromagnetic induction or corona discharge.

   Common mistake: Confusing polarisation with electrostatic shielding inside conductors

2. Question 2 · easy · Conductors and electrostatic shielding

   For a conductor of any shape in electrostatic equilibrium, carrying any amount of net charge and placed in any external electric field, the electric field at every point inside the bulk of the conducting material is

   • A.equal to the external applied field, unaffected by the conductor
   • B.zero only if the conductor is uncharged
   • C.always zero
   • D.zero only if the conductor is spherical in shape
   Show answer and explanation

   Answer: C. always zero

   In electrostatic equilibrium, free charges redistribute on the conductor's surface until the field inside the bulk material is exactly zero, regardless of the conductor's shape, net charge, or any external field.

   A conductor contains free (mobile) charge carriers. If a field existed inside the material, those carriers would experience a force and keep moving, so the situation would not be electrostatic equilibrium. Hence, in equilibrium, the free charges rearrange themselves (on the surface) precisely so that the field everywhere inside the conducting material is zero. This holds true for a conductor of any shape, any amount of net charge, and any external field — it's a general and fundamental property of conductors in electrostatics, not limited to symmetric shapes or the uncharged case.

   Common mistake: Believing the zero-field result depends on the conductor being uncharged or a special shape.

3. Question 3 · medium · Conductors and electrostatic shielding

   An isolated positively charged conducting sphere, far from any other charges, is connected to the earth by a long conducting wire. What happens?

   • A.An equal amount of negative charge flows from the earth onto the sphere, making it neutral by addition rather than removal
   • B.Nothing happens, because there is no nearby negative charge to attract the positive charge away
   • C.Positive charge flows from the sphere to the earth until the sphere's potential becomes zero, essentially neutralizing it
   • D.The sphere becomes more positively charged, since the earth is effectively an infinite source of charge
   Show answer and explanation

   Answer: C. Positive charge flows from the sphere to the earth until the sphere's potential becomes zero, essentially neutralizing it

   The earth acts as a large conductor at (reference) zero potential. Connecting the positively charged sphere to earth lets positive charge flow away until the sphere's potential also drops to (essentially) zero, so it becomes practically uncharged.

   Grounding (earthing) connects a conductor to the earth, which is treated as an enormous conductor of effectively infinite capacitance held at potential zero (the reference). When the positively charged sphere (at some positive potential) is connected to the earth via a wire, charge flows through the wire from the higher-potential sphere to the lower-potential earth — driven purely by the potential difference, with no need for a nearby opposite charge. This flow continues until the sphere's potential equals that of the earth (zero), meaning virtually all the excess positive charge has drained away, leaving the sphere practically neutral. This is a common source of confusion: grounding works via potential equalization, not via any 'attraction' from a specific opposite charge.

   Common mistake: Believing charge flow to earth requires an explicit nearby opposite charge, rather than understanding it as potential equalization.

4. Question 4 · easy · Conductors and electrostatic shielding

   A conductor of arbitrary shape, carrying some net charge, is placed in an external electrostatic field. Once electrostatic equilibrium is reached, the net electric field at any point inside the bulk of the conductor's material is

   • A.zero, because free charges redistribute over the surface until the field due to them exactly cancels the external field inside
   • B.equal to the external field alone, since conduction electrons cannot affect the field deep inside the material
   • C.equal to the field due to the conductor's own charge alone, with the external field entirely blocked at the surface
   • D.non-zero but the same at every interior point, regardless of the conductor's shape
   Show answer and explanation

   Answer: A. zero, because free charges redistribute over the surface until the field due to them exactly cancels the external field inside

   In electrostatic equilibrium, free charges in a conductor always redistribute themselves so that the net field (external + induced) inside the conducting material is exactly zero.

   A defining property of a conductor in electrostatic equilibrium is that free charges move until the interior field vanishes; if any field remained, the free charges would continue to experience a force and move, contradicting equilibrium. This redistribution happens regardless of the conductor's shape or the presence of an external field — the induced surface charges always arrange themselves to produce a field inside that exactly cancels any external field, leaving zero net field throughout the conductor's bulk. This is a foundational and very frequently tested NEET fact underlying electrostatic shielding.

   Common mistake: Believing the field is merely reduced, rather than exactly zero, inside the conductor.

5. Question 5 · medium · Conductors and electrostatic shielding

   Coaxial cables carrying signals are surrounded by a braided conducting shield, usually connected to ground. The main electrostatic reason this shield protects the inner signal wire from external electrical interference is that

   • A.the shield is a conductor in electrostatic equilibrium, so charges induced on it produce a field that cancels any external field within the enclosed region, keeping the interior free of external fields
   • B.the shield physically absorbs all external electric charge before it can reach the inner wire
   • C.the shield increases the effective resistance along any path a stray field might take, weakening it before it reaches the inner wire
   • D.the shield reflects the external field back toward its source, similar to how a mirror reflects light
   Show answer and explanation

   Answer: A. the shield is a conductor in electrostatic equilibrium, so charges induced on it produce a field that cancels any external field within the enclosed region, keeping the interior free of external fields

   A conducting shield in equilibrium develops induced surface charges that produce a field cancelling the external one inside the enclosed region — the standard electrostatic shielding (Faraday cage) mechanism.

   When an external electric field is present near a conductor, free charges redistribute on the conductor's surface until the net field inside the conducting material (and any enclosed cavity) is zero. Applied to a coaxial cable's braided shield, this means any external interfering field induces a surface charge distribution on the shield that exactly cancels the external field within the region enclosed by the shield, where the actual signal-carrying inner conductor sits. This is precisely the electrostatic shielding principle, not a matter of charge absorption, resistive weakening, or field reflection.

   Common mistake: Attributing shielding to charge absorption or field reflection rather than induced-charge cancellation.

6. Question 6 · medium · Charge and Coulomb's law

   When a glass rod is rubbed with silk, the glass rod becomes positively charged and the silk becomes negatively charged. A student concludes that the rubbing process creates brand-new positive charge on the glass rod. What is the correct interpretation?

   • A.Charge is created only on the rod; the negative charge on the silk arises independently through a separate process.
   • B.Rubbing creates equal amounts of positive and negative charge out of nothing, later balanced by contact with the ground.
   • C.The glass rod's protons migrate to the silk cloth during rubbing, making the glass positive.
   • D.Rubbing transfers electrons from the glass rod to the silk; no charge is created, and the total charge of the (rod + silk) system is conserved.
   Show answer and explanation

   Answer: D. Rubbing transfers electrons from the glass rod to the silk; no charge is created, and the total charge of the (rod + silk) system is conserved.

   Charging by friction is electron transfer, not charge creation; the total charge of the isolated rod-silk system remains exactly conserved.

   In triboelectric charging, loosely bound electrons transfer from one material to the other on contact/rubbing. The glass rod loses electrons (becoming positive) and the silk gains exactly that many electrons (becoming equally negative). No charge is created or destroyed; total charge before and after rubbing is the same (zero, if both started neutral). Protons remain fixed in nuclei and never transfer during ordinary rubbing.

   Common mistake: Believing charge is generated from nothing during rubbing, rather than merely transferred.

7. Question 7 · easy · Electric field and field lines

   Which of the following statements about electric field lines is correct?

   • A.Two field lines can cross each other at a point where the net field happens to be zero.
   • B.Electric field lines always form closed loops encircling a positive point charge.
   • C.Electric field lines are always perpendicular to the surface of a conductor in electrostatic equilibrium.
   • D.The number of field lines drawn from a charge is independent of the magnitude of the charge.
   Show answer and explanation

   Answer: C. Electric field lines are always perpendicular to the surface of a conductor in electrostatic equilibrium.

   At the surface of a conductor in electrostatic equilibrium, the field must be perpendicular to the surface; any tangential component would drive surface charges to move.

   In electrostatic equilibrium, charges on a conductor's surface are stationary, which is only possible if there is no field component tangential to the surface (otherwise charges would experience a force along the surface and move). Hence field lines meet the conductor surface perpendicularly. Field lines never cross (the field direction at any point is unique), never form closed loops around a static point charge (that is a magnetic-field property), and their density is meant to represent field strength/charge magnitude, not be independent of it.

   Common mistake: Confusing electric field lines (which never form closed loops around static charges) with magnetic field lines.

8. Question 8 · hard · Electric field and field lines

   A student claims: 'Since electric field lines never cross, the field lines produced by two different nearby point charges must stay perfectly parallel everywhere and never intersect at any point.' Which statement correctly evaluates this claim?

   • A.The claim is entirely correct; field lines from any set of charges are always parallel to each other.
   • B.Field lines from two equal charges actually do cross exactly at the midpoint between them.
   • C.Field lines only avoid crossing when the two charges are of like sign; for unlike charges they can cross.
   • D.Field lines from different charges never cross at any single point (since the field direction there would then be double-valued), but they are not parallel — near each charge they diverge or converge radially.
   Show answer and explanation

   Answer: D. Field lines from different charges never cross at any single point (since the field direction there would then be double-valued), but they are not parallel — near each charge they diverge or converge radially.

   Field lines never cross anywhere (else the field direction at that point would be ambiguous), but this does not make them parallel — near any point charge, its own field lines spread out radially.

   The 'no crossing' rule follows from the fact that the electric field at any point has a single, well-defined direction; if two field lines crossed, the field at that intersection would have two different directions simultaneously, which is impossible. This rule holds for any combination of charges, regardless of sign. However, it does not imply the lines are parallel: close to any individual point charge, its field lines radiate outward (or inward) in all directions, clearly non-parallel. The student's error is over-generalizing the non-crossing property into a false claim of parallelism.

   Common mistake: Over-extending the true 'field lines never cross' rule into the false claim that field lines must be parallel.

Questions about Electrostatics for NEET

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Questions are original NEET720 compositions reviewed for correctness, syllabus fit and option quality. Counts update as the bank grows (1,047 active practice questions in this chapter today).