Physics · Conductors and insulators, dielectrics and electric polarization

The uncharged metallic sphere suspended as shown in the given figure is given a

The uncharged metallic sphere \( \mathbf{A} \) suspended as shown in the given figure is given a push so that it moves towards the +ve plate. Which of the following statements is correct?

  • A. A touches the positive plate and remains in contact with it
  • B. A touches positive plate and then moves towards negative plate and remains in contact with it.
  • C. A moves to and fro between the two plates with a constant time period
  • D. A moves to and fro between the two plates with an increasing time period.

Step-by-step solution

Initially uncharged, sphere A is pushed towards the positive plate. Upon touching, it acquires positive charge, is repelled from the positive plate, and attracted to the negative plate. It then touches the negative plate, acquires negative charge, and repeats the process. The electric field between the plates is uniform, so the force on the charged sphere has constant magnitude. For small oscillations (assuming a pendulum setup) or if gravity is negligible, the acceleration is constant, leading to a constant time of flight between plates. Thus, the sphere oscillates with a constant period.
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