Start learning →

OJEE Electric Charges and Fields — practice questions

Explore 29 free Electric Charges and Fields questions in OJEE Physics. Open each question or exercise to read its content, reference answers and available explanation.

Practise Electric Charges and Fields with Quill →

Electric Charges and Fields questions and exercises with answers

Showing questions 1–29 of 29.

Quantisation of electric charge means:Read the answer and worked solution →If 10⁹ electrons leave a body every second, the time required to accumulate a total charge of 1 C is approximately:Read the answer and worked solution →A charge of −12 nC is given to a body. The number of excess electrons on the body is:Read the answer and worked solution →Coulomb's law in vacuum is F = (1/4πε₀)(q₁q₂/r²). The value of 1/4πε₀ is approximately:Read the answer and worked solution →Two point charges q₁ and q₂ separated by distance r in vacuum experience force F. If both charges are doubled AND the distance is halved, the new force is:Read the answer and worked solution →The SI unit of electric field is:Read the answer and worked solution →The electric field on the **equatorial line** of a dipole (perpendicular bisector, r >> a) has magnitude:Read the answer and worked solution →A dipole of moment p is placed in a uniform external field E. The torque on the dipole is:Read the answer and worked solution →A dipole of moment 10⁻²⁹ C·m is placed in a uniform field of 10⁵ N/C at angle 30°. The torque on the dipole is:Read the answer and worked solution →If a point charge is placed **outside** a closed Gaussian surface, the total flux through the surface is:Read the answer and worked solution →For a uniformly charged thin spherical shell of radius R and total charge Q, the electric field INSIDE the shell (r < R) is:Read the answer and worked solution →Linear charge density λ has SI units:Read the answer and worked solution →NEET · Physics · Electric Charges & Fields · Coulomb's Law — Gap FillRead the answer and worked solution →NEET · Physics · Electric Charges & Fields · Quantity to UnitRead the answer and worked solution →NEET · Physics · Electric Charges & Fields · Conductor or InsulatorRead the answer and worked solution →NEET · Physics · Electric Charges & Fields · Gauss's Law — MemoryRead the answer and worked solution →NEET · Physics · Electric Charges & Fields · Tap Like-Charge PairsRead the answer and worked solution →NEET · Physics · Electric Charges & Fields · Field at a PointRead the answer and worked solution →NEET · Physics · Electric Charges & Fields · Dipole or Monopole FieldRead the answer and worked solution →NEET · Physics · Electric Charges & Fields · Dipole Moment — Gap FillRead the answer and worked solution →NEET · Physics · Electric Charges & Fields · Force on Dipole in FieldRead the answer and worked solution →NEET · Physics · Electric Charges & Fields · Electric Field — TypingRead the answer and worked solution →NEET · Physics · Electric Charges & Fields · Quantity to FormulaRead the answer and worked solution →NEET · Physics · Electric Charges & Fields · Tap Field-Line PropertiesRead the answer and worked solution →NEET · Physics · Electric Charges & Fields · Field Inside or OutsideRead the answer and worked solution →NEET · Physics · Electric Charges & Fields · Capacitance — Gap FillRead the answer and worked solution →NEET · Physics · Electric Charges & Fields · Field of a Charged ShellRead the answer and worked solution →Judge a dipole sitting in a fieldRead the answer and worked solution →Drop each fact inside or outsideRead the answer and worked solution →

Worked practice questions

Quantisation of electric charge means:

  1. Charge can take any continuous value
  2. All free charges are integral multiples of the elementary charge e (1.602 × 10⁻¹⁹ C)
  3. Only positive charges are quantised
  4. Charge is always zero
Show answer and solution

Correct answer: B. All free charges are integral multiples of the elementary charge e (1.602 × 10⁻¹⁹ C)

**Quantisation of charge**: q = ne, where n is an integer (positive or negative) and e = 1.602 × 10⁻¹⁹ C (charge on proton; electron has -e). At macroscopic scales (1 μC ≈ 6 × 10¹² electrons) quantisation is unobservable matters only at microscopic level.

Open this question →

If 10⁹ electrons leave a body every second, the time required to accumulate a total charge of 1 C is approximately:

  1. 200 days
  2. 200 hours
  3. 200 years (≈ 6.25 × 10⁹ seconds)
  4. 2 hours
Show answer and solution

Correct answer: C. 200 years (≈ 6.25 × 10⁹ seconds)

**Charge per second:** 10⁹ × 1.6 × 10⁻¹⁹ = 1.6 × 10⁻¹⁰ C/s. **Time for 1 C:** 1 / (1.6 × 10⁻¹⁰) = 6.25 × 10⁹ s = 6.25 × 10⁹ / (365 × 24 × 3600) ≈ **198 years ≈ 200 years**. Shows 1 C is a very large unit for electrostatics.

Open this question →

A charge of −12 nC is given to a body. The number of excess electrons on the body is:

  1. 7.5 × 10¹⁰
  2. 1.92 × 10⁻²⁷
  3. 7.5 × 10¹⁹
  4. 1.92 × 10¹⁰
Show answer and solution

Correct answer: A. 7.5 × 10¹⁰

n = |q|/e = (12 × 10⁻⁹) / (1.6 × 10⁻¹⁹) = **7.5 × 10¹⁰ electrons**. Body is negatively charged → excess electrons (matches the −12 nC sign).

Open this question →

How to practise

  1. Choose a Electric Charges and Fields question and try to work out your answer.
  2. Open the question to check the correct answer and read its worked solution.
  3. Continue in the app for bite-sized lessons, explanations and review with Quill. You can start without creating an account.

More Physics topics

MagnetismKinetic Theory of GasesWork and EnergyWork and PowerCurrent ElectricityElectromagnetismOpticsMagnetism and Matter