Question

charging a conducting rod
this problem explores the behavior of charge on
conductors. we take as an example a long conducting rod
suspended by insulating strings. assume that the rod is
initially electrically neutral. for convenience we will refer to
the left end of the rod as end a, and the right end of the rod
as end b
figure
1 of 1
part a
a small metal ball is given a negative charge, then brought near to end a of the rod (figure 1). what happens to end a of the rod when the ball
approaches it closely this first time?
view available hint(s)
it is repelled.
it is attracted.
it is neither attracted nor repelled.
submit
now consider what happens when the small metal ball is repeatedly given a negative charge and then brought into contact with end a of the rod
part b

Explanation:

Part A

When a negatively charged metal ball is brought near end A of a neutral conducting rod, electrostatic induction occurs. The negative charge on the ball repels the free electrons in the rod (since like charges repel), causing the electrons in the rod to move towards end B. This leaves end A with a net positive charge (as electrons have moved away). Since opposite charges attract, the positively charged end A will be attracted to the negatively charged ball.

Answer:

B. It is attracted.