question_answer

Five balls, numbered 1 to 5 are suspended using separate threads. Pairs (1, 2), (2, 4), (4, 1) show electrostatic attraction, while pairs (2, 3) and (4, 5) show repulsion. What is the nature of charge on ball 1?

Answer:

                Repulsion is the surest test of electrification. So balls 2, 3, 4 and 5 are electrically charged. Pairs (2, 3) and (4, 5) are similarly charged. As pair (2, 4) shows attraction, so balls 2 and 4 are oppositely charged. If balls (2, 3) are positively charged, then (4, 5) be negatively charged or vice versa. The ball 1 is attracted both by 2 and 4 separately i.e., by both kinds of charges. Hence the ball 1 is neutral.