Question

A small uncharged metallic sphere is positioned exactly at a point midway between two equal and opposite point charges. If the sphere is slightly displaced towards the positive charge and released then

• A. it will oscillate about its original position
• B. it will move further towards the positive charge
• C. its electric potential energy will decrease and kinetic energy will increase
• D. its total energy remains constant but is non-zero

Answer 1

Answer: (D)

Initially the force on the sphere is equal due to both $-ve$ and $+ ve$ charge.
$\therefore $ Net force $=0$
On displacing the sphere towards the $+ve$ charge, force on sphere due to $+ve $ charge will be more than due to the $-ve$ positive charge, because it is nearer.
So, sphere will move further to the charge.