The diagram shows a large conducting sphere X mounted on an insulating pillar. The sphere X is given a positive charge. The small, uncharged metal sphere S, suspended on an insulating thread, is brought near X.
(a) Show on the diagram the charges induced on S.
(b) What will happen to sphere S? Explain your answer.
(c) S is moved horizontally so that it touches X. Explain what happens to S.
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Answer:
(a)
(b) S will be attracted by X. This is because negative charges are induced nearer to sphere X whereas the positive charges induced are further away from X. Thus, there is a net attractive force between the sphere X and S.
(c) When S touches X, some electrons flow from S to X and S is now positively charged (Note: S was originally neutral). Since X also possess positive charges, repulsion occurs and S moves to the right, away from X.
