Two fixed charges `-2Q` and `+Q` are located at points `(-3a,0)` and `(+3a,0)` respectively. Then which of the following statement is correct?

Answer

3

Explanation

On x-axis, potential will be undefined ( or say + `oo`) at x = 3a and x = - 3a , because charge Q and -2Q are placed at these two points . So , between `-3a lt x lt 3a` we can find potential by putting y = 0 in Eq .
(i) Therefore ,
`V = (Q)/( 4 pi epsi_(0)) [(1)/(3a -x) - (2)/(3a + x)^(2) + y^(2)`
On simplifiying , we get `(x - 5a)^(2) + y^(2) = (4a)^(2)`
For ` x gt 3 a` there again a point where potential will become zero so for we can write
`V = (Q)/( 4 pi espi_(0)) [(1)/(3a - x) -(2)/(3a + x)] ` for `x lt - 3a `
In this region potential will be zero only at ` x to oo`
thus we can summariese it as under .
(i)