Two point charge `-q` and `+q//2` are situated at the origin and the point `(a,0,0)` respectively. The point along the `X`-axis where the electic field Vanishes is

Options

A. `x=(sqrt2a)/(sqrt2-1)`
B. `X=sqrt2a-sqrt2-1`
C. `x=(sqrt2-1)sqrt2a`
D. None of these

Answer

A

Explanation

Let us consider the field varies at distance x, as we have

`(kq)/(x^(2))=(kq//2)/((x-a)^(2))`
`rArr" "2(x-a)^(2)=x^(2) rArr sqrt2(x-a)=x`
`rArr" "(sqrt2-1)x=sqrt2a`
`rArr" "x=(sqrt2a)/(sqrt2-1)`