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Most Important Selected Qs for JEE AdvancedPhysicsElectrostatics

Figure shows four charges fixed on the vertex of a square in horizontal plane. A charged bead is constrained to move along a wire which passes through centre of square & perpendicular to its plane. Mark the correct statement(s).

Options

  1. AIn gravity free space a positively charged bead cannot be in stable equilibrium at any position.
  2. BIn gravity free space a negatively charged bead cannot be in stable equilibrium at any position.
  3. CIn presence of gravity a negatively charged bead cannot be in stable equilibrium at any position above the pla
  4. DIn presence of gravity a positively charged bead cannot be in stable equilibrium position above the plane of f

Correct answer

C. In presence of gravity a negatively charged bead cannot be in stable equilibrium at any position above the pla

Step-by-step solution

In space (gravity not zero) net force on +q is vertically upward. So that equilibrium can be achieved in the space. If charge is -q then net force on it is vertically downward so equilibrium not achieved.

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