Five balls numbered 1 to 5 are suspended using seperate threads . Pairs (1,2) (2,4)(4,1) show electrostatic attraction
Hello,
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As per your question, if some pairs have been attracted then they might be the pair which gets charged through induction or just by a touch.
There are 3-4 ways for charging to get an object electrostaticly charged. This might be due to induction or convention.
Better to ask your physics teacher to explain you out with basics.
Hope it helps!