Several pith balls are suspended by nylon string of negligible mass. Ball B is negatively charged. Ball A attracts Ball B. Ball A repels Ball C. Which statement about the charges on the other balls is true?

A) Ball A is negatively charged.

B) Ball A is neutral.

C) Ball C is positively charged.

D) Ball C is neutral.

Answer: option C) Ball C is positively charged.

Justification:

1) Remember charges of equal sign repel each other and charges of opposite sign atract each other.

2) With that:

i) Given that ball B is negatively charged and ball A attracts Ball B, you conclude that ball A is positively charged.

ii) Given ball A repels ball C, you conclude ball C is positively charged.