A small charged ball is hovering in the state of equilibrium at a height h over a very large horizontal uniformly charged sheet. If a disc of radius r `( lt lt h ) `, is removed from the plate directly underneath the ball, then the acceleration of the ball will be

A small charged ball is hovering in the state of equilibrium at a height h over a very large horizontal uniformly charged sheet. If a disc of radius r (r lt lt h ) , is removed from the plate directly underneath the ball, then the acceleration of the ball will be

A charged particle having some mass is resting in equilibrium at a height H above the center of a uniformly charged non-conducting horizontal ring of radius R . The equilibrium of the particle will be stable .

A charged particle having some mass is resting in equilibrium at a height H above the center of a uniformly charged non-conducting horizontal ring of radius R . The equilibrium of the particle will be stable .

A charged particle having some mass is resting in equilibrium at a height H above the centre of a uniformly charged non-conducting horizontal ring of radius R . The equilibrium of the particle will be stable .

A small iron ball falls from rest through a large height h into a water column, the final velocity

A small iron ball falls from rest through a large height h into a water column, the final velocity

A small positively charged ball of mass m is suspended by an insulating thread of length L. This ball remains in equilibrium with string horizontal when another small charged ball is placed exactly at a distance L below the point of suspension of the first ball. The second ball is slowly moved away from the first ball to a far away point. (The second ball is moved horizontally so that the first ball does not accelerate). As a result the first ball lowers down to the original position of the second ball and the string become vertical. Find the work done by the external agent in removing the second ball.

A small ball of mass m=21 g suspended by a insulating thread at a height h=12 cm from a large horizontal conducting plane performs small oscillations (figure) . After a charge q had been imparted to the ball, the oscillation period changed eta=2.0 times. Find q .