Question

Five balls numbered $1,2,3,4$ and $5$ are suspended using separate threads. The balls $(1,2),(2,4)$ and $(4,1)$ show electrostatic attraction, while balls $(2,3)$ and $(4,5)$ shown repulsion. Therefore, ball $1$ must be :

• A. negatively charged
• B. positively charge
• C. neutral
• D. made of metal

Answer 1

Answer: (C)

neutral

$12345$
$+-+$
If $1$ is positively charged, then $2$ should be negatively charged, then $4$ should be positively charged. Now, $1$ and $4$ cannot attract. It means ball $1$ should be neutral ($2$ and $4$ cannot be neutral because they are showing repulsion with $3$ and $5$, respectively).