Question

Three charges 2q, -q, -q are located at the vertices of an equilateral triangle. At the centre of the triangle

• A. The field is zero but potential is non-zero
• B. The field is non-zero but potential is zero
• C. Both field and potential are zero
• D. Both field and potential are non-zero

Answer 1

The correct option is B The field is non-zero but potential is zero

Obviously, from charge configuration, at the centre electric field is non-zero. Potential at the centre due to 2q charge is $V_{2q}=\frac{2q}{r}$

and the potential due to – q charge is
$V_{-q}=-\frac{q}{r}$ (r = distance of centre)
$\therefore$ Total potential $V=V_{2q}+V_{-q}+V_{-q}=0$