Question

what happens if you rub two pith balls with a piece of wool? answer options: select one of four they become negatively charged and attract each other. they become positively charged and attract the wool. they become negatively charged and repel each other. they lose all charge and have no effect on each other.

Explanation:

When rubbing pith balls with wool, the pith balls gain electrons from the wool, becoming negatively charged (since wool tends to lose electrons and pith balls gain them in this triboelectric interaction). Objects with the same charge (both negative here) repel each other. Let's analyze the options:

• First option: Same - charged objects repel, not attract. So this is wrong.
• Second option: Pith balls become negative (not positive) when rubbing with wool (wool is more likely to be positive after losing electrons). Also, the question is about the interaction between the two pith balls, not with wool. So this is wrong.
• Third option: Pith balls gain electrons (negative charge) and since both have the same negative charge, they repel each other. This matches the physics of static electricity (like charges repel).
• Fourth option: Rubbing transfers charge, so they won't lose all charge. This is wrong.

Answer:

They become negatively charged and repel each other.