A positively charged light metal ball is suspended between two oppositely charged metal plates on an insulating thread as shown below. After being charged once, the plates are disconnected from the battery. Describe the behavior of the ball.
Would the ball remain in the center?
The plates are still charged.
You did not say that the plates were connected to each other so that the charges went away.
The positively charged ball will be attracted to the negatively charged plate.
I think the ball will rebound back and forth, carrying charge from one plate to the other, until the plates are discharged.
It starts like this: the + ball moves to the -plate, touches it, and becomes negative, whence it is repelled toward the + plate, touches it, discharges, becomes postive again, and moves back to the negative plate, and so on.
Wouldn't it be like charging a battery and the plates remain charged?
I have the same exact question as BAdams did in 2008! I was wondering if anyone could explain this in further detail.
A positively charged light metal ball is suspended between two oppositely charged metal plates on an insulating thread as shown below. After being charged once, the plates are disconnected from the battery. Describe the behavior of the ball.
Thank you so much!
To understand the behavior of the positively charged light metal ball, we need to consider the forces acting on it.
When the plates are connected to a battery, they become charged and create an electric field between them. The positive charge on the ball experiences an electrostatic force due to this electric field.
The electrostatic force is attractive between opposite charges and repulsive between like charges. In this case, the positive ball will experience an attractive force towards the negatively charged plate.
However, since the ball is also suspended on an insulating thread, it is under the influence of two other forces: gravity and tension in the thread.
Gravity pulls the ball downwards, while the tension in the thread pulls the ball upwards to balance the gravitational force.
When the system is in equilibrium, meaning the forces are balanced, the ball will come to rest at a position where the gravitational force, tension force, and the electrostatic force are balanced.
In this specific configuration, with the oppositely charged plates, the ball will move towards the negatively charged plate due to the attractive electrostatic force. As it moves closer to the plate, the tension in the thread will increase to counteract the increased electrostatic force, until a new equilibrium is reached.
So, the behavior of the ball in this setup is that it will move towards the negatively charged plate and come to rest at a new equilibrium position. It will not remain at the center.