Question

Two charges $Q_1=18\mu C$ and $Q_2=-2\mu C$ are separated by a distance R, and $Q_1$ is on the left of $Q_2$. The distance of the point where the net electric field is zero is :

• A. between $Q_1$ and $Q_2$
• B. left of $Q_1$ at R/2
• C. right of $Q_2$ at R
• D. right of $Q_2$ at R/2

Answer 1

The correct option is D right of $Q_2$ at R/2

A. between $Q_1$ and $Q_2$ , electric field due to both charges will be in same direction so net electric field can not be zero in that direction. Hence A is wrong
B.left of Q1 electric field dut to $Q_1$ will always be higher than $Q_2$ because
$Q_1\ge Q_{2}and{r}_1\le r_2$. Hence B is wrong
C. $\frac{k{Q}_2}{x^2}=\frac{k{Q}_1}{(x+R{)}^2}$ or $x=\frac{R}{2}$
Therefore C is wrong and D is correct