Charges `+q` and `-2q` are fixed at distance d apart as shown in fig.
(i) sketch roughly the pattern of electric field lines, showing the positon of neutral point.
(ii) Where should a charge partical q be placed so that it experience no force ?
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Explanation

Let the net force on q at P be zero. Then,
`(kq^(2))/(x^2)=(kq 2q)/((d+x)^(2))` or `x=(d)/(sqrt(2)-1)`

P is the netural potential where where electric field will be zero.