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JEE Main Electrostatic Potential and Capacitance — practice questions

Explore 30 free Electrostatic Potential and Capacitance questions in JEE Main Physics. Open each question or exercise to read its content, reference answers and available explanation.

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Electrostatic Potential and Capacitance: quick revision

Potential is a scalar, so signed potentials add algebraically. A potential difference is energy transferred per unit charge. For a capacitor, identify whether charge or voltage stays fixed before changing its geometry or dielectric.

Key ideas and when to use them

  • Point-charge potential: $V=kq/r$, taking zero at infinity.
  • $Q=CV$.
  • Capacitor energy: $U=\tfrac12CV^2=Q^2/(2C)$.

Common mistakes

  • The sign of potential follows the charge; potential is not a vector.
  • A disconnected capacitor keeps its charge, whereas an ideal connected battery fixes its voltage.

Three worked examples

Example 1: Find the potential 0.20 m from a +2 μC point charge. Take zero at infinity and k = 9 × 10⁹.
  1. Use signed charge in $V=kq/r$.
  2. $V=(9\times10^9)(2\times10^{-6})/0.20$.

90000 V

Example 2: A 2 μF capacitor is connected across 5 V. Find its charge in μC.
  1. Use consistent micro-units: μF × V gives μC.
  2. $Q=2\times5$.

10 μC

Example 3: A 4 μF capacitor has potential difference 10 V. Find its stored energy in μJ.
  1. Use $U=\tfrac12CV^2$ with C in farads.
  2. $U=\tfrac12(4\times10^{-6})10^2=200\times10^{-6}$ J.

200 μJ

Qallery AI-assisted study notes and original examples. Further reading: NCERT Physics — Electrostatic Potential and Capacitance.

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Electrostatic Potential and Capacitance questions and exercises with answers

Showing questions 1–30 of 30.

Potential is defined as work done per unit test charge so that the result:Read the answer and worked solution →Which is physically significant, the actual value of potential or the potential difference?Read the answer and worked solution →Bringing a unit positive charge from infinity to a point, without acceleration, measures the point's:Read the answer and worked solution →Volta built the first battery from a stack of metal disks and moist:Read the answer and worked solution →A surface where the potential has the same value at every point is called:Read the answer and worked solution →Around a single point charge the equipotential surfaces are:Read the answer and worked solution →At any point the electric field meets the equipotential surface:Read the answer and worked solution →In a uniform field along x, the equipotential surfaces are planes:Read the answer and worked solution →The electric field points in the direction in which the potential:Read the answer and worked solution →Inside a conductor in the static situation, the electrostatic field is:Read the answer and worked solution →You charge a metal ball. Where does the excess charge sit?Read the answer and worked solution →The electrostatic potential inside and on the surface of a conductor is:Read the answer and worked solution →Dielectrics differ from conductors because they have:Read the answer and worked solution →In O2 and H2 molecules the centres of positive and negative charge coincide. They are:Read the answer and worked solution →Two conductors separated by an insulator form a:Read the answer and worked solution →A capacitor's plates carry Q and minus Q. The total charge of the capacitor is:Read the answer and worked solution →The ratio Q/V for a capacitor is a constant called its:Read the answer and worked solution →A capacitor with a large capacitance can hold a large charge at a:Read the answer and worked solution →The largest field a dielectric can withstand without breaking down is its:Read the answer and worked solution →A parallel plate capacitor is two large flat plates separated by a:Read the answer and worked solution →Capacitors in series all carry:Read the answer and worked solution →Capacitors in parallel all have:Read the answer and worked solution →Catch the conductor factsRead the answer and worked solution →Pop the non-polar moleculesRead the answer and worked solution →Steer into the potential laneRead the answer and worked solution →Slice the capacitor wordsRead the answer and worked solution →Conductor or dielectricRead the answer and worked solution →Series or parallelRead the answer and worked solution →One word is wrongRead the answer and worked solution →Potential and capacitance bingoRead the answer and worked solution →

Worked practice questions

Potential is defined as work done per unit test charge so that the result:

  1. Does not depend on q
  2. Doubles with q
  3. Is always zero
  4. Depends on the path
Show answer and solution

Correct answer: A. Does not depend on q

1. The work on a test charge is proportional to q. 2. Dividing by q removes that dependence. 3. So the result is independent of q. _Source: syllabus Physics Part I, Chapter 2, Electrostatic Potential and Capacitance._

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Which is physically significant, the actual value of potential or the potential difference?

  1. Only the sign
  2. The difference
  3. The actual value
  4. Neither of them
Show answer and solution

Correct answer: B. The difference

1. The zero of potential can be chosen freely. 2. Only changes in potential do work. 3. So the potential difference is what matters. _Source: syllabus Physics Part I, Chapter 2, Electrostatic Potential and Capacitance._

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Bringing a unit positive charge from infinity to a point, without acceleration, measures the point's:

  1. Electrostatic potential
  2. Electric field strength
  3. Surface charge density
  4. Capacitance value
Show answer and solution

Correct answer: A. Electrostatic potential

1. Infinity is the chosen zero of potential. 2. The work done per unit charge from there is the definition. 3. It is the electrostatic potential at the point. _Source: syllabus Physics Part I, Chapter 2, Electrostatic Potential and Capacitance._

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