# Answer to Question #35594 in Electromagnetism for Reem

Question #35594

A small suspended metallic ball A carriesba positive charge . A charged metallic rod B is brought close to it . We observe that B attracts A , A and B touch each other and then repel each other. What was the sign of the charge on the rod ? Explain what you observed . What would have happened if the two charges had equal magnitudes ? Thxx :))

Expert's answer

If charged rod attracts metallic ball(ball carries the positive charge), the rod has negative charge.

After A and B touched each other, they had equal potentials.

If after that they repel each other, they have equal charge. If initial value of charge of rod is larger than the charge of ball, the final charges of two bodies are positive, because summary charge are constant. If initial value of charge of rod is smaler than the charge of ball, the final charges of two bodies are negative.

if the two charges had equal magnitude, after contact the ball and rod don't interact because they became electrically neutral (summary charge is zero, charges after contact of bodies are zero).

After A and B touched each other, they had equal potentials.

If after that they repel each other, they have equal charge. If initial value of charge of rod is larger than the charge of ball, the final charges of two bodies are positive, because summary charge are constant. If initial value of charge of rod is smaler than the charge of ball, the final charges of two bodies are negative.

if the two charges had equal magnitude, after contact the ball and rod don't interact because they became electrically neutral (summary charge is zero, charges after contact of bodies are zero).

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