Five balls numbered 1 to 5 are suspended using separate threads. Pairs $(1,2),(2,4)$ and ( 5 , 1) sh

Question

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

Professor PC Thomas Classes · Answer

$A$ is attraction and $R$ repulsion\ Case I: Let 1 has +ve charge. Then 2 must have -ve charge and 4 must have +ve charge 5 must have +ve charge. Then there can not be attraction between 1 and 5 . But the problem says there is attraction between 1 and 5. Therefore our assumption that 1 is + ve wrong. Case II: Let 1 have -ve charge. The 2 must have +ve charge, $4-$ ve charge and 5 must have -ve charge. Then there can not be attraction between 1 and 5 . Hence our assumption that 1 is -ve is wrong. Then there can be only one more assumption.\ ie. 1 must be neutral\