Q48 / 57 · JEE Advanced 2021 (Paper 1) · Physics
Two point charges $-Q$ and $+Q / \sqrt{3}$ are placed in the $x y$-plane at the origin $(0,0)$ and a point $(2,0)$, respectively, as shown in the figure. This results in an equipotential circle of radius $R$ and potential $V=0$ in the $x y$-plane with its center at $(b, 0)$. All lengths are measured in meters.

The value of is ________ meter.

The value of is ________ meter.
Correct answer: 3
Solution
Let be be a general point with potential to be zero.

(as potential given )
Standard equation of circle is given by
and
Hence,
and value of
Hence, the correct answer is 3.