A balloon and a section of a wall both have neutral charges, as shown below.

Question

A student rubs his hair on the balloon, giving it a negative charge. How will the charges be arranged in the wall when it is placed near the negatively changed balloon?

Answer 1

When the negatively charged balloon is brought near the neutral wall, it will induce a separation of charges in the wall due to electrostatic induction. Here's how it works:

1. Induction Process: The negatively charged balloon exerts a repulsive force on the electrons in the wall (which are negatively charged). This causes the electrons in the wall to move away from the balloon, creating a region of positive charge near the balloon and a region of negative charge further away.

2. Charge Distribution: As a result of this movement:

   • The area of the wall closest to the balloon will have a positive charge, as electrons are repelled away from that area.
   • The area of the wall farthest from the balloon will have a negative charge, as some electrons have moved away from the region near the balloon.

3. Overall Charge: Despite the movement of electrons, the wall remains electrically neutral overall because no charges are added or removed from the wall—only redistributed.

In summary, when the negatively charged balloon is near the neutral wall, the wall will develop a positive charge in the area closest to the balloon and a negative charge farther away, leading to an induced polarization of the wall's charges. The wall will be attracted to the negatively charged balloon due to this polarization.