A negatively charged plastic ruler repels a lightweight, insulated sphere suspended from a thread.
What can be concluded about the charge on the sphere?
The sphere must be charged positively.
The sphere must be charged negatively.
The sphere must be neutral (uncharged).
The sphere could be either negatively charged or neutral.
145 exam-style questions on CIE IGCSE Physics 4.2.1a Positive and negative charge. Each one has a worked solution and a mark scheme showing where the marks go.