Question

Two charges Q and -2Q are placed at some distance. the locus of points in the plane of the charges where the potential is zero will be

• A. Straight line
• B. Circle
• C. Parabola
• D. ellipse

Answer 1

The correct option is C Parabola

Two charges $Q$, $-2Q$

some distance

Potential $=0$

hence,

$\frac{1}{4\pi {ϵ}_0}\times \frac{Q\times (-2Q)}{R}=0$

When we use it the parabolic condition then,

$y^2=4ax⟶\left(1\right)$

Now,

$\frac{1}{4\pi {ϵ}_0}\times \frac{Q\times 2Q}{R}=0$

$\frac{{2Q}^2}{R}=0⟶\left(2\right)$

Hence, equating $\left(1\right)$ and $\left(2\right)$ and we get, the system is getting parabola.