Physics · Electric charges: conservation of charge, Coulomb's law forces between two point charges, forces between multiple charges, superposition principle and continuous charge distribution

The bob of a pendulum is positively charged. Another identical charge is placed

The bob of a pendulum is positively charged. Another identical charge is placed at the point of suspension of the pendulum. The time period of pendulum

  • A. increases
  • B. decreases
  • C. becomes zero
  • D. remains same

Step-by-step solution

The electrostatic force between the two identical charges is repulsive and acts along the string, which is radial. For small oscillations, the tangential restoring force depends only on gravity (mg sinθ), and the radial force does not affect the torque about the suspension point. Therefore, the equation of motion remains unchanged, and the time period T = 2π√(L/g) stays the same.
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