Question

Two charges of $10\mu C$ and $-20\mu C$ are separated by a distance of $20cm$. The distance of the point from smaller charge where electric potential is zero if it lies between them is :

• A. $\frac{3}{20}cm$
• B. $6.67cm$
• C. $10cm$
• D. $16cm$

Answer 1

The correct option is B $6.67cm$

Let x be the distance from $10\mu c$ where potential is zero
$\Rightarrow 0=\frac{k\left(10\mu C\right)}{x}+\frac{k(-20\mu C)}{20-x}$

$\Rightarrow 0=\frac{10}{x}-\frac{20}{20-x}$

$\Rightarrow (20-x)10=20x$
$\Rightarrow 20=3x$

$\Rightarrow x=\frac{20}{3}=6\cdot 67cm$