JEE Physics · Hard

Electrostatics: Charge Distribution MCQ

Solve this quality-checked JEE multiple-choice question, then review the correct answer and explanation.

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Charge DistributionHardQuestion 31489

Question

Two conducting spheres of radii R₁ and R₂ connected by a long wire. In equilibrium, surface charge densities σ₁ and σ₂ satisfy:
  1. A
    σ₁ = σ₂
  2. B
    σ₁R₁ = σ₂R₂
    Correct
  3. C
    σ₁/R₁ = σ₂/R₂
  4. D
    σ₁R₁² = σ₂R₂²

Correct answer

σ₁R₁ = σ₂R₂

Explanation

Connected spheres: same potential V = kQ₁/R₁ = kQ₂/R₂. σ = Q/(4πR²). kσ×4πR²/R = const → σR = const → σ₁R₁ = σ₂R₂. Smaller sphere has higher σ (and higher E at surface).