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Question: Answered & Verified by Expert
A thin spherical shell of radius R is cut into two equal halves and then each of its halves is charged to the same uniform surface charge density σ. If F is the force exerted on each half to keep them at equilibrium, then F is proportional to

PhysicsMagnetic Properties of MatterJEE Main
Options:
  • A 1 ε 0 σ 2 R
  • B 1 ε 0 σ 2 R
  • C 1 ε 0 σ 2 R 2
  • D 1 ε 0 σ 2 R 2
Solution:
2421 Upvotes Verified Answer
The correct answer is: 1 ε 0 σ 2 R 2
Electrical force per unit area = 1 2 ε 0 E 2 = 1 2 ε 0 σ ε 0 2 = σ 2 2 ε 0

Projected area = π R 2

   Net electrical force = σ 2 2 ε 0 π R 2

In equilibrium, this force should be equal to the applied force.

   F = π σ 2 R 2 2 ε 0

or    F σ 2 R 2 ε 0

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