Three charges 4q,Q and q are in straight line in the position o,l/2 and l respectively the resultant force on q will be zero

Dear pallavi

two force are acting on q ,one due to 4q and second due to Q

F1 = 1/4∏ε (4q)q/l² 

F2 = 1/4∏ε (Q)q/(l/2)² 

      = 1/4∏ε (4Q)q/l² 

 F1 +F2 =0

1/4∏ε (4q)q/l²   +  1/4∏ε (4Q)q/l²  =0

 Q=-q

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