JEE Advanced 2021 Paper 1 · Q10 · Electric Potential

Question

Two point charges $-Q$ and $+Q/\sqrt{3}$ are placed in the $xy$-plane at the origin $(0,\,0)$ and at the point $(2,\,0)$, respectively. All lengths are measured in metres. This arrangement produces an equipotential circle of radius $R$ and potential $V = 0$ in the $xy$-plane, with its centre at $(b,\,0)$. The value of $b$ is ___ metre.

SolveKar AI · Accepted Answer

From Q9, the equipotential V = 0 circle meets the x-axis at a = 2√3/(√3+1) and C = 2√3/(√3−1). Centre b = (a + C)/2 = √3 · [1/(√3−1) + 1/(√3+1)] = √3 · [(√3+1+√3−1)/((√3)²−1)] = √3·(2√3/2) = 3. Hence b = 3.00 m.

JEE Advanced 2021 Paper 1 · Q10 · Electric Potential

Solution