Question

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, therefore ball $1$ must be?

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

Answer 1

The correct option is A

neutral

Determine Charge of ball $1$:

1. It is given that pairs $(1,2)(2,4)(4,1)$ show electrostatic attraction while pairs $(2,3)$ and $(4,5)$ show repulsion.
2. The pair $\left(2,4\right)$ exhibits attraction towards each other which means that they have opposite charges.
3. Since the pair $\left(1,2\right)$ is also attractive towards each other, which means that ball $1$ and $4$ must have the same charge and should undergo repulsion.
4. But, we see that the pair $\left(1,4\right)$ also show attraction toward each other, therefore ball $1$ must be neutral and it shows attraction due to the induction of charges.

Hence, option $\left(A\right)$ is the correct answer.