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 charged balloon?

The charges in the wall will not change or rearrange at all
The wall will now have all positive charges and no negative charges
The wall will have its positive charges on the side closer to the balloon
The wall will have negative charges on the side closer to the balloon

Answer 1

When a negatively charged balloon is brought near a neutral wall, the charges in the wall will rearrange. Specifically, the negative charges (electrons) in the wall will be repelled by the negatively charged balloon, causing them to move away from the side of the wall that is closer to the balloon. This leaves behind a region of positive charge (due to the lack of electrons) on the side of the wall that is nearer to the balloon.

Therefore, the correct statement is:

The wall will have its positive charges on the side closer to the balloon.